Sometimes the air and 
earth potentials temporarily go 180 degrees out of phase with 
each other. Examples of these can be seen in Figure 1-
In summary, it is seen that the electrical environment correl­
ates with tree potentials while the more obvious meteorological 
parameters such as light, temperature, and pressure do not in any 
immediate sense. 3 
The absolute range of Burr's tree potentials is 0 to 500 milli­
volts. Sign is arbitrary and defined initially by Burr making the 
upper electrode positive. Polarity can reverse with changes in 
season or large perturbations in potential. Typical values until 
1963 were 20 to 100 mY, and subsequen tly 200 to 400 mv. The 
reason for this increase is unknown. The most obvious characteristic of tree potential records is a 
diurnal cycle, easily seen by inspection. This cycle is typically a 
minimum in the early morning hours and a maximum during 
the afternoon. It may vary in magnitude and in phase from day 
to day, while larger magnitude and phase differences are apparent 
from season to season. The range of diurnal variation of tree potentials during the 
winter months is two or three times that of the summer. The 
magnitude of tree potentials shows a yearly cycle, a minimum in 
April, a maximum in September (see Figure 2). In considering the 
significance of maxima and minima it is necessary to recall that 
the upper electrode was arbitrarily assigned to be positive. So in 
essence the seasonal (yearly) cycle shows two inflection points 
around the time of the equinoxes. Burr believed he could detect a monthly periodicity in tree 
potentials related to phase of the moon. Confirmation of the 
validity of this finding awaited more extensive statistical analy sis 
\vhich will be discussed later in this report. Analysis of all reduced data (a 15-year period) suggests that the 
tree potentials are in phase with the sunspot cycle (see Figure 3). 170 +10r----r--�----�--_r----r_--_r--_,----._ ·--�----�--_ 
+5 
,.... 
> 
5 0 
-10 
.J F M A M " 
I \ I 
I \ I I � 
I \ \ I Mon thly Ave. I " 
3-Month Running 
Mean 
J J A S 0 
Months 
Figure 2. Tree potential monthly averages (1946-1961). +50 200 
+40 180 
+30 160 
+20 140 
� .. 
.0 
+10 g 120 
z 
,.... ... > o � 100 E ...... .. " " 
80 -10 <II 
... .... 
-20 � 60 
-30 40 
-40 20 Sunspots 
Potential 
Smoothed 
_ 50 0 L--'---'--'- ......... .."..... '-- '-- ..L..- '-'---'---'- ----1--'_'- ..L..-.J 
1946 47 48 49!J) 5.1 52 53 54 55 56 57 58 59 60 61 
Year , 
, 
, 
, 
N D 
Figure 3. Yearly average tree potentials and sunspot numbers. 171 SE LE CTED PAPERS 
Since one sunspot cycle lasts about II years a longer time series 
is necessary to establish the relationship more firmly. To investig­
ate the possible importance of solar activity it was decided to 
check the geomagnetic activity index against tree potentials. This analysis will be described. As noted above, during the early phases of his work, Burr 
simultaneously measured two trees which were 40 miles apart. Similarities in these records suggest that they were responding to 
the same external force which was not local in nature. Besides the diurnal variation, the other easily seen charac­
teristic in Burr's tree pot-ential records occurs during the period 
approxima tely from 10 p.m. to midnight until dawn, when 
there is little variation (noise) in the record. Around dawn the 
noise increases and continues until after sunset. The exact onset 
and termination of the noisier period varies, and on some days 
this effect is absent. There is no immediate explanation for the 
phenomenon; it is not dependent on light or noise in the power­
lines. A day's record of tree potentials illustrating the midnight-till­
dawn quiet period and typical characteristics of such records was 
seen in Figure 1. 4 
Burr's work showed that the electric field of biological systems 
was a sensitive indicator of biological activity. There were 
indications that in some applications the electric field would be 
used to predict biological activity before it happened. This was 
evidence for the hypothesis that the electric field of a living 
system regulated its structure and functioning. The question then remained as to which factors in the en­
vironment might modulate the electric field of living systems. The commonly considered environmental paramet ers were found 
not to have immediate influence, although they probably would 
on a long-term basis, perhaps accounting (at least in part) for the 
observed seasonal variations. However, less obvious environ­
mental factors, the electric fields in the atmosphere and earth, did 
1]2 SELECTED PAPERS 
correlate with tree potentials and thus may influence biological 
activity. Burr also found indications that the moon's position and solar 
activity influenced tree potentials. This may possibly occur 
through their modulation of the electro-magnetic environment. The use of the earth's magnetic field as a geophysical parameter 
was suggested by the possibility that the magnitude of tree 
potentials fluctuated with the II-year sunspot cycle. The geo­
magnetic field which undergoes variations following solar erup­
tions provides the best long-term quantitat ive data for solar­
terrestrial research. The earth's magnetic field is continuously recorded at many 
observatories throughout the world. Arbitrary scales have been 
developed to express quantitatively fluctuations in the strength 
and direction of the magnetic field. In the late 1930S, Bartels 
developed the A and K indices which have subsequently been 
used throughout the world. These had the advantage over the 
previous system of being objectively determined. The A index is 
first obtained using linear measures of the magnitude and varia­
tions of the graphic records. This is transformed to the K index 
through an arbitrarily defined quasilogarithmic relationship. The 
range of the A index is 0 to 400 while the range of the K index is 
o to 9. The conversion table is given below. K 0 1 z 3 4 S 6 1 8 9 
A 0 4 1 15 z7 48 80 140 z4° 400 
Certain magnetic observatories report their eight daily values, 
one each for 3-hour periods,�wh ich are averaged to determine the 
planetary magnetic indices Ap and Kp. Normalizing factors are 
applied to each observatory since magnetic fluctuations are 
greater near the auroral zones. In investigating the possible re­
lationship of tree potentials to geomagnetic activity, it was de­
cided to use the Ap index because it is a linear measure and does 
not overly weigh the weaker disturbances. The technique of superposed-epoch analysis- sometimes 
simply called 'epoch analysis'-was utilized to see if geomagnetic 
173 SEL ECTED PAPERS 
activity was associated with fluctuations in tree potential. Values of tree potential were tabulated for six days before to six 
days after specific 'key days'. This 13-day span constitutes an 
epoch. Key days were chosen with no advance knowledge of tree 
potentials by scanning daily Ap values. When a day was found 
in which the index rose sharply to values at least twice as high 
as previously-after periods of at least a week when the index 
was relatively low and steady-such days were designated as key 
days. During solar minimum the low and steady periods had Ap 
values below 10, while near solar maximum low and steady Ap 
values were about 15. Calling the key day the nth day, averages 
were obtained of the tree potential values for each day from the 
n -6th to the n + 6th. This analysis was done separately for each 
year studied. Approximately 20 key days per year were chosen 
for the years 1953, 1955, 1957, 1959, and 1961. These years span 
one sunspot cycle from minimum to minimum. Because the magnitude and variation of tree potentials change 
for different seasons and years, it was necessary to normalize this 
parameter. The original tree potentials were tabulated in 24-
hourly readings per day. Only the midnight values were used as 
representative of each day, because this was a time of minimum 
'noise' as seen in Figure 1. If solar activity, as manifest by the magnetic index, is related 
to tree potentials, one might expect to find anomalous tree poten­
tials on the key days, or afterward if there was a lag in the tree's 
response. The basic question one must ask in this form of analysis 
is, 'How do you know an anomalous value of tree potential on 
a particular day is associated with magnetic activity?' A causal 
relationship between magnetic activity and tree potential cer­
tainly cannot be implied if an abnormal fluctuation in tree poten­
tial occurs before a solar outburst. However, even if a statistical 
correlation were found, it would not necessarily imply causality; 
both parameters could he controlled by some other variable(s). 174 SE LEC TED PAPER S 
5 
In order to formulate a reasonable hypothesis to test with 
epoch analysis, it is necessary to consider how solar activity 
modulates the earth's magnetic field. The sunspot index (Wolf 
Number) is a crude measure of solar activity, determined simply 
from the number and grouping of visually observed sunspots. Areas of large sunspots often produce strong solar flares; but 
flares can also occur in solar regions without sunspots. Solar flares produce ultraviolet radiation and sometimes x-rays 
and high-energy cosmic rays. These forms of radiation propagate 
at or near the speed of light reaching the earth in about eight to 
fifteen minutes, where they cause ionization and electric currents 
in the ionosphere. In turn the ionospheric disturbances cause 
variations in the magnetic field which, when strong enough, are 
called 'magnetic storms'. Flares also produce corpuscular radiation particles which pro­
pagate more slowly, reaching the earth in about one or two days. When these charged particles hit the upper atmosphere, they also 
produce ionization. Some are trapped in the magnetosphere, 
where they are temporarily stored. When sufficiently accelerated 
in the magnetosphere, they may penetrate deep enough into the 
atmosphere to cause auroras. Perturbations of the earth's mag­
netic field are associated, with these events. Thus magnetic storms occur at two times: (1) Immediately 
after a solar flare-due to wave radiation, and (2) Some time after 
the solar flare (generally two to four days)-due to corpuscular 
radiation. Although it is known that solar particles take about two days 
to reach the earth and magnetic storms often commence at that 
time, R. Reiter* has found that the Kp index becomes a maximum 
on the fourth day following a solar flare. Magnetic storms gener­
ally last several days and should not be considered as single 
events. Additional bundles of solar particles may reach the upper 
* Reiter, Reinhold. Relationships between atmospheric electrical 
phenomena and simultaneous meteorological conditions, Air Force 
Cambridge Research Lab. No. 415. Vol. 1, 169-171, 1960. 175 SELEC TED PAPERS 
atmosphere over a period of several days following a solar erup­
tion. Thus the magnetic disturbance is perpetuated with one 
magnetic storm superimposed upon the next. The total period of 
enhanced magnetic activity is typically two or three days and 
sometimes longer. Therefore, a lag of four days between solar 
flares and maximum of the magnetic index is not inconsisten t 
with the model. We can therefore answer the question of what day or days in 
an epoch might display anomalous tree potentials if they are 
associated with magnetic activity. Assuming little or no delay in 
the response of the tree itself, the maximum deviation of tree 
potentials should occur on the key day which was chosen as 
having a large increase in magnetic index. Some of these days 
would correspond to the class of magnetic storms caused by wave 
radiation and occur shortly after a flare. According to Reiter's results one would also expect a second­
ary peak in the tree potential curve on the (n + 4)th day. The nth­
day (key day) effect should be strongest as all these days have 
magnetic storms, while the (n + 4)th-day effect should be weaker 
not being precisely timed, i.e., there is an enhanced probability 
of magnetic activity on the (n + 4)th day, but only some of these 
days would actually have magnetic storms. Figure 4 is the result of the five years studied covering one sun­
spot cycle and a total of 100 epochs. The maximum tree potential 
variation occurs on the key day. It exceeds the average by 2'3 
standard deviations (the 98/� confidence level). A secondary peak of about I standard deviation occurs on the 
(n + 4)th day. While not statistically significant, this is the only 
other maximum in the curve. Both maxima occur on the two days 
postulated in the original hypothesis to fit the model. We can conclude from the result of this analysis that tree 
potentials respond either to geomagnetic activity directly, or that 
both parameters may be under the in�uence of some other geo­
physical factor or factors. 176 '" 
...... 
'"' +.05 
Ii=: 0 I 
P.. 
t.-.0 5 I i···· ... _ .. _. -I i -,-- -! : 
__ � ___ L __ _ J. __ J ___ : __ _ �-.... -. . .--- .. -.. -.. -.. 
i . , . i 
1(f--- --�-
-.10 -- : ........... . I 
I 
-.15 _.-L _ ... _ 
2(f-----�--
I 
-.2�L 6----�_5L--- -_j4----- _�3-----_2�---- _�1----��� +�l-.--��--��-- �+4��� +5�--� +::6 
Figure 4. Results of superposed-epoch analysis correlating tree potentials with 
geomagnetic activity. Midnight values used for years 1953, 1955, 1957, 1959. 
and 1961-total epochs studied = 100. (TP -TP) / s = Normalized Tree Potential Variation. TP = Midnight tree potential 
TP = Monthly mean of TP s = Standard devia tion of each epoch 
IT = Standard deviation of this curve � �3S 14n--r---r------r-----�------�----_,------,_----�,_----, -------r_----_, 
"-l ., 00 .... 
4J I< 
c; '1/ 
�30 1h2 
o I-< 
p... U 
'1/ .... 
�2S �lO 
� H � \ 
� �)!J \ ic Index 
-;:: . ?J20 b. 8 I--H'--V---+-�-I---_+_ --_.- ---.. ----- --.. -.--t----�-. -_t_--_; 
�.g < " ... � � � IS 6 
4J 
U 
'1/ 
0. C/l 10 4 
5 2 
o O�----�----�------�----�-----L------�----��--�--���---� 
o .05 .10 .15 .20 .25 .30 .35 .40 
Frequency (cycles per day) 
Figure 5. Ap-magnetic index and midnight -tree-potential spectra. January 1953 
through December 1960 (2922 days, 100 lags). Numbers at peaks are period of 
harmonics in days. .45 .50 SELEC TED PAPERS 
6 
In order to test for possible periodicities in the tree potential 
records that could be attributed to the solar-activity period of 
27'3 days or to the lunar synodic period of 29'5 days, spectrum 
analysis was utilized, with the aid of the IBM 7074 computer at 
the Pennsylvania State University. Such analysis would indicate what periodicities, if any, were 
present in the tree potential. Both solar and lunar influences had 
been suggested by Burr in his earlier work; spectrum analysis 
might bring out the relative importance of each, and possibly 
other, environmental influences. Two time series were utilized; tree potentials at midnight and 
tree-potential changes at dusk for 2922 days starting with the 
year 1953. While no periodicity was found in the dusk tree 
potential changes, significant periodicity appeared in the mid­
night tree potentials. Figure 5 shows the Ap index and midnight 
tree potential spectra. The 27-day sunspot period is clearly seen 
in the former but is not present in the latter. Coherence between 
the spectra is small and not significant. This does not mean that 
there is no relationship between the magnetic index and midnight 
tree potentials. Because the relationship between magnetic storms 
and tree potentials is probably much weaker than the relationship 
between sunspot position and magnetic storms, which is weak to 
start with, it Would be expected that little coherence would exist 
in cross-spectrum analysis between the Ap index and midnight 
tree-potential spectra. For this reason, according to Brier, * the 
superposed-epoch analysis is superior to spectrum analysis in 
bringing out weak relationships. The midnight tree-po ten tial spectrum shows peaks with 
periods of: 12'5,7'15,4'76,3.85,3'08,2.63, and 2·10 days. This 
suggested that the peaks were the 2nd, 4th, 6th, 8th, loth, 12th, 
and 14th harmonics of a fundamental frequency near 27'3 or 
29'5 days (sunspot repetition or lunar synodic periods). Multiply-
* Brier, Glenn. Statistics section. U.S. Weather Bureau. personal 
communication. 179 SE LEC TED PAPERS 
ing each peak period by its corresponding harmonic and taking 
the mean, we find 29'5 days, the synodic period of the moon. The question arises as to whether these peaks are really har­
monics of some fundamental frequency. If so, a plot of the peak 
frequency as ordinate against the harmonic as abscissa would 
result in a straight line. Figure 6 shows such a plot which is close 
to a straight line. The slope of the solid line, which fits the data 
well, would be for the moon's synodic period of 29'5 days. The 
dashed line was drawn by fitting the points using the method of 
least squares and gives a period of 30'3 days, close to the lunar 
synodic period. The sunspot period is represented by the dotted 
line and is well beyond the range of deviation of data points from 
the line of best fit. This analysis points to the moon and not the 
sun as influencing tree potentials. It is important to note that the fundamental period of the 
moon is not present in the midnight tree-potential spectrum; only 
the even harmonics are seen. This means the basic frequency is 
really 14.75 days or half the synodic period; implying a semi­
monthly tidal mechanism. The same period was found by Brier 
and Bradley* in their researches on lunar control of rainfall and 
is also seen in ocean and atmospheric tides. The tree-potential spectrum suggests a lunar gravitational 
mechanism occurring twice a month when the moon is in con­
junction and opposition with the sun. It is possible that the moon 
is not directly influencing the tree potential with its gravitational 
field but through the electro-magnetic environment which is 
modulated by the tidal period. Statistically, both the sun and the moon seem to in�uence 
tree potentials, the sun apparently through an electro-magnetic 
mechanism, the moon through a gravitational or gravitational­
electrical mechanism. The moon's effect is more easily detected. It is possible that the lunar effect is not a gravitational one 'per 
se', but one of modulation of the tree's electro-magnetic environ­
ment. * Brier, G., and Bradley, D. A. The lunar synodical period and 
precipitation in the United States, J. Atmos. Sci., 21, 386-395, 1964. 180 ... 
00 ... ... , 
o 
>. u 
C 
<II 
::J .5[...----.----.------.----.--.------.--....--.- -.--,.---'..-----,.-. .' ./ / / 
.' / .' / .' / 
.4 Lunar Synodic (29.5) -2 ..... · .. � 
.��� 
Sunspot (27.3) � .•.• �/ 
c.,.. .' /-<// ········�//o·2-
"/ 
"/ 
"/ 
:/ .. /' 
•. ' /' Least Squares (30.3) 
/' 
/'" l � 
I 
·1 
I 
g.2 ,,' :/ ..... , � I ... 
rio< 
.1 
0.' . ..... .' '7 .' � 
" � 
.' '/' .' 'Y 
.' '/' 
.' 'Y 
.. ;;''Y 
I 
I 
o 1.!' __ -L. __ .L..-_......L. __ -'--_--'-__ ...I-_-' __ -J ___ '-- _ ...1.. __ � _ _L •.. __ -L. __ <-- . __ � .. _j 
o 1 2 3 4 5 6 6 8 9 10 11 12 13 14 i5 16 
Figure 6. Analysis of harmonics in midnight-tree-potential spectrum showing 
lunar synodic period. Numbers in parentheses are periods in days which are the 
reciprocal of the line's slope. SE LECTED PAPERS 
7 
This study has suggested further researches that could use­
fully be pursued in the future: 
Superposed-epoch analyses suggested response of tree poten­
tials to rapid increases in the magnetic index. In future research, 
the validity of this finding could be checked by utilizing the un­
analysed data for 1954, 1956, 1958, and 1960. The exact period present could also be obtained by superposed­
epoch analysis, using a modified technique sllch as Brier's in 
establishing the lunar periodicity in rainfall. The advantage of 
the technique is that it makes possible high resolution of periodi­
cities in a time series with only one value per day. Spectrum analysis utilizing but one value per day and limited 
to a maximum lag of 100 cannot pinpoint the exact period by 
means of hourly values (which are available). If the tree potential 
spectrum could be examined in high resolution for the range 
between 27-and 30-day periods the exact period could be de­
termined. Prior to 1962, Burr's data are available only in tabulated form 
with hourly values. from 1962 through 1966, the original records 
are available. One typical day is seen in figure 1. Evaluation of 
these records would allow for better statistical analysis. They 
show restlessness in the trace as well as discontinuous changes in 
mean tree potential. These transients may illustrate basic be­
haviour of tree potentials, and may lead to an understanding of 
the mechanisms by which tree potentials respond to the environ­
ment. The signal-to-noise ratio in these data is much higher than in 
the earlier records. for some unknown reason, around 1963 
typical absolute magnitudes increased from below 100 mv. to 
200-400 mv., which may allow environmen tal influences to be 
isolated that were previously undetectable. The typical tree potential records contain 'quiet time' periods 
between about midnight and dawn. Some days do not display this 
characteristic, and the onset and termination of this period is 
182 SELEC TED PAP ERS 
variable. In the future, it would be of interest to analyse this 
phenomenon in relation to meteorological, geophysical, and 
seasonal variables. Inspection of the later records clearly shows that tree poten­
tials, air potential, and earth potential are generally exactly in 
phase. However, sometime s only one tree responds or the air 
anel earth potentials go to 180 degrees out of phase. Analysis in 
regard to the meteorological-geophysical environment may ex­
plain these phenomena. In 1966, the maple tree which provided the records used in this 
analysis was dying. Finally it had to be cut down. Continuous 
records are available for this tree from 1962 on. Simultaneous 
records are available for an elm tree which stood next to the 
maple. It was noted that the magnitude of electrical potential in 
the maple tree when it was dying remained the same as before, 
but the characteristic fluctuations in the record (see Figure 1) be­
came much smaller or ceased, while the healthy elm tree dis­
played its normal fluctuations in phase or out of phase with the 
air and earth potentials. This interesting phenomenon should be 
analysed. The effect of imposing electric, magnetic, and electro-m agnetic 
radiation fields on the electrical potential of living systems can 
be studied in the laboratory, with fields of the order of those 
occurring naturally. Animals and plants might be studied simul­
taneously in order to determine whether or not different living 
systems respond simultaneously to changes in the electro-mag ­
netic environment. Also, if electrical potential is a function of 
the state of health one would expect to see characteristic differ­
ences'in the electrical records of disturbed, sick, or dying systems. Such responses might eventually serve as a diagnostic tool. If the electric field of living systems is an indicator of biological 
activity and possibly a regulator of it, then geophysical factors 
may be of extreme importance for men venturing into space, so 
that measurements of their electrical potential, along with other 
biomedical parameters, might well have to be considered. Such 
information may provide the answer to how man's geophysical 
environment affects him and may give clues to the classical 
183 SE LEC TED PAPERS 
mystery of biological clocks. The understanding and use of 
electrical potentials in living systems may be an important part 
of the new 'space age' science of exobiology. APPENDIX 
BIB LIO GRAPHY OF 
HAROLD SAXTON BURR 
1916 
1. The effects of the removal of the nasal pits in Amblystoma 
embryos. J. expo Zool., 1916, 20: 2757. 2. Regenera tion in the brain of Amblystoma. J. compo Neurol., 
1916,26: 203-211. 1918 
3. Breeding habits, maturation of eggs and ovulation of the 
albino rat. Amer. J. Anat., 1918, 15: 291-317. 1920 
4. The transplantation of the cerebral hemispheres of Ambly­
stoma. J. expo Zool., 1920, 30: 159-169. 1922 
5. The early development of the cerebral hemispheres in Ambly­
stoma. J. compo Neurol., 1922, 34: 277-301. 1924 
6. An experimental study of the origin of the meninges. Proc. Soc. expo BioI. (N.Y.), 1924, 22: 52-53 (with S. C. Harvey). 7. Some experiments on the transplantation of the olfactory 
placode in Amblystoma. 1. An experimentally produced 
aberrant cranial nerve. J. compo Neurol., 1924,37: 455-479. 1925 
8. An anatomical study of the gasserian ganglion, with par­
ticular refrence to the nature and extent of Meckel's cave. Anat. Rec., 1925, 29: 269-289 (with G. B. Robinson). APPENDIX 
1926 
9. An experi mental study of the action of hyoscine hydrobro­
mide on the nervous system of Amblystoma. J. compo 
Neurol., 1926, 41: 401-421. 10. The developm ent of the meninges. Arch. Neurol. Psychiat., 
1926, 15: 545-565 (with S. C. Harvey). 1928 
11. Certain factors determining the direction of growth of nerve 
fibres. Science, 1928, 74: 604. 12. The central nervous system of Orthagoriscus mala. J. camp. Neural.. 1928, 45: 33-128. 1929 
13. Jonathan Knight and the founding of the Yale Medical 
School. Yale J. Biol. Med .• 1929. 1: 327-343. 1930 
14. Hyperplasia in the brain of Amblystoma. J. expo Zool., 1930, 
55: 171-191. 15. Disciplines. Yale J. BioI. Med., 1930, 3: 151-157. 1931 
16. The preclinical sciences and human biology. Yale J. Biol. Med., 1931, 4: 63-68. 17. Development of the meninges in the chick. Proc. Soc. expo 
Bio!. (N.Y.), 1931, 28: 974-976 (with S. C. Harvey). 1932 
18. Determinants of organization in the cerebral hemispheres. Res. Publ. Ass. nerv. ment. Dis., 1932, 13: 39-48. 19. An electro-dynamic theory of development suggested by 
studies of proliferation rates in the brain of Amblystoma. J. 
camp. Neural., 1932,56: 347-371. 1933 
20. Development of the meninges. Arch. NeuraL Psychiat., 
1933,29: 683-690 (with S. C. Harvey). 186 APP END IX 
1934 
21. The founding of the Medical Institution of Yale College. Yale J. Biol. Med., 1934,6: 333-340. 22. Some observations on the neural mechanisms of Opistho­
proctus Soleatus Vaillant. Psychiat. neurol. Br., 1934, 38: 
407-416 (with G. M. Smith). 23. Sympathetic components of the genit o-femoral and obtura­
tor nerves in the Rhesus monkey (Macaca mulatta). Anat. Rec., 1934, 61: 53-56 (with S. Zuckerman). 1935 
24. A study of the effects of intermedin and injury of the hypo­
physis on traumatic corial melanophores in goldfishes. Endo­
crinology, 193), 19: 409-412 (with G. M. Smith and R. S. 
Ferguson). 25. The electro-dynamic theory of life. Quart. Rev. Bio!., 193), 
10: 322-333 (with F. S. C. Northrop). 26. Electrical characteristics of living systems. Yale J. BioI. Med., 
1935, 8: 31-3) (with C. T. Lane). 27. Detection of ovulation in the intact rabbit. Proc. Soc. expo 
Bio!. (N.Y.), 1935, 33: 109-111 (with R. T. Hill and Edgar 
Allen). 1936 
28. Electro-dynamic studies of mice with developing cancer of 
the mammary gland. Anat. Rec., 1936, 64: 7-8. 29. A vacuum tube microvoltmeter for the measurement of bio­
electric phenomena. Yale J. Biol. Med., 1936, 9: 65-76 (with 
C. T. Lane and 1. F. Nims). 30. Bio -electric phenomena associated with menstruation. Yale 
J. BioI. Med., 1936, 9: 155-158 (with 1. K. Musselman). 1937 
31. Experimental findings concerning the electro-dyn amic 
theory of life and an analysis of their physical meaning. Growth, 1937, 1: 78-88 (with F. s. C. Northrop). 32. Bio-electric potential gradients in the chick. Yale J. BioI. Med., 1937, 9: 247-258 (with C. I. Hovland). APPEN DIX 
33. Bio-electric correlates of developm ent in Amblystoma. Yale 
J. Biol. Med., 1937,9: 541-549 (with C. I. Hovland). 34. Medical fees in the colonial period. Yale J. Bio!. Med., 1937, 
9: 359-364-
35. A bio-electric record of human ovulation. Science, 1937,86: 
312 (with 1. K. Musselman, D. Barton, and N. Kelley). 36. Bio-electric correlates of human ovulation. Yale J. Bio!. Med .• 
1937. 10: 155-160 (with 1. K. Musselman. D. Barton. and 
N. Kelley). 1938 
37. Steady-state electrical properties of the human organism dur­
ing sleep. Yale ]. BioI. Med .• 1938, 10: 271- 274 (with D. S. 
Barton). 38. Bio-electric properties of cancer-resistant and cancer-suscept­
ible mice. Amer. J. Cancer, 1938, 32: 240-248 (with 1. C. 
Strong and G. M. Smith). 39. Bio-electric correlates of the menstrual cycle in women. Amer. J. Obstet. Gynec .• 1938, 35: 743-751 (with 1. K. 
Musselman). 40. Bio-electric correlates of methylcolanthrene-induc ed tumours 
in mice. Yale J. BioI. Med., 1938, 10: 539-544 (with 1. C. 
Strong and G. M. Smith). 41. The relationship between the bio-electric potential of rats 
and certain drugs. Yale J. BioI. Med., 1938, 11: 137-140 
(with P. K. Smith). 42. The measurement of pH in circulating blood. Science, 1938, 
87: 197-198 (with 1. F. Nims and Clyde Marshall). 43. Bio-electric correlates of wound healing. Yale J. BioI. Med., 
1938, 11: 104-107 (with S. C. Harvey and Max Taffel). 1939 
44. Evidence for the existence of an electro-dynamic field in liv­
ing organisms. Proc. nat. Acad. Sci., 1939, 25: 284-288 (with 
F. S. C. Northrop). 45. A preliminary study of electrical correlates of growth in 
Obelia geniculata. Growth, 1939, 3: 211-220 (with Fred S. 
Hammett). 188 APPE NDIX 
46. Voltage gradients in the nervous system. Trans. Amer. neuraL Ass., 1939, 65: 11-14 (with P. J. Harman, Jr.). 47· Vocationalism in the university. Yale J. Biol. Med., 1939, 
12: 199-204. 48. Animal electricity. Yale scient. Mag., 1939, 13: 5. 1940 
49. Biologic organization and the cancer problem. Yale J. BioI. Med., 1940, 12: 277-282. 50. Vaginal electrical correlates of the estrous cycle of the rat. Anat. Rec., 1954, 76: 8 (With John Boling and D. Barton). 51. An electro-metric study of the healing wound in man. Yale J. 
BioI. Med., 1940, 12: 483-485 (with Max Taffel and S. C. 
Harvey). 52. Harry Burr Ferris. Science, 1940, 92: 499-500. 53. Electro-metric studies of tumours induced in mice by the 
external application of benzpyrene. Yale J. BioI. Med., 1940, 
12: 711-717 (with C. M. Smith and 1. C. Strong). 1941 
54. Factors associated with vaginal electrical correlates of the 
estrous cycle of the albino rat. Anat. Rec., 1941, 79: 9 (with 
John Boling). 55. Field properties of the developing frog's egg. Proc. nat. Acad. Sci., 1941, 27: 276-281. 56. Changes in the field properties of mice with transplanted 
tumours. Yale J. BioI. Med., 1941, 13: 783-788. 57. An electro-metric study of uterine activity. Amer. J. Obstet. Gynec., 1941, 42: 59-67 (with 1. Langman). 58. Steady state potential differences in the early development of 
Amblystoma. Yale J. Biol. Med., 1941, 14: 51-57 (with T. H. 
Bullock). 1942 
59. An electrical study of the human cervix uteri. Anat. Rec., 
1942, 82: 35-36 (with 1. Langman). 60. Electrical correlates of growth in corn roots. Yale J. Bior. Med., 1942, 14: 581-588. APPE NDIX 
61. Electro-metric timing of human ovulation. Amer. J. Obstet. Gynec., 1942, 44 : 223-230 (with 1. Langman). 1943 
62. Neuroid transmission in mimosa. Anat. Rec., 1943,85: 12. 63. Electrical correla tes of pure and hybrid strains of corn. Proc. nat. Acad. Sci., 1943, 29: 163-166. 64. Electrical polarization of pacemaker neurons. J. N euro­
physio!., 1943, 6: 85-97 (with T. H. Bullock). 65. An electro-metric study of mimosa. Yale J. BiD!. Med., 1943, 
15: 823-829. 1944 
66. Moon-madness. Yale J. BiD!. Med., 1944, 16: 249-256. 67. A biologist considers social security. Conn. St. med. J., 1944, 
8: 165. 68. Potential gradients in living systems and their measurements. Pp. 1117-1121 in Medical Physics. Chicago, The Year Book 
Publishers, Inc. [Cl944]. 69. The meaning of bio-electric potentials. Yale J. Bio!. Me.d., 
1944, 16: 353-360. 70. Electric correlates of form in Cucurbit fruits. Amer. J. 
Botany, 1944,31: 249-253 (with E. W. Sinnott). 71. Electricity and life: phases of moon correlated with life 
cycle. Yale scient. Mag., 1944, 18: 5-6. 1945 
72. Variables in DC measurement. Yale J. BiD!. Med., 1945, 17: 
465-478. 73. Diurnal potentials in the maple tree. Yale J. BiD!. Med., 1945, 
17: 727-734. 1946 
74. Electrical correlates of peripheral nerve injury. A prelimin­
ary note. Science, 1946, 103 : 48-49 (with R. G. Grenell). 75. Growth correlates of electromotive forces in maize seeds. Proe. nat. Acad. Sci., 1946, 32: 73-84 (with Oliver Nelson, 
Jr.). APPEN DIX 
76. Surface potentials and peripheral nerve injury: A clinical 
test. Yale J. BioI. Med., 1946, 18: 517-525 (with R. G. 
Grenell). 1947 
77· Tree potentials. Yale J. BioI. Med., 1947, 19: 311-318. 78. Electro-magnetic studies in women with malignancy of cer­
vix uteri. Science, 1947, 105: 209-210 (with 1. Langman). 79· Field theory in biology. Sci. Monthly, 1947,64: 217-225. 80. Surface potentials and peripheral nerve regeneration. Fed. Proc., 1947,6: 117 (with R. G. Grenell). 1948 
81. A commentary on full-time teaching. Conn. St. med. J., 1948, 
12: 937-940. 1949 
82. Millivoltmeters. Yale J. BioI. Med., 1949, 21: 249-253 (with 
A. Mauro). 83. A technique to aid in the detection of malignanc y of the fe­
male genital tract. Amer. J. Obstet. Gynec., 1949, 57: 274-
281. 84. Electro-static fields of the sciatic nerve in the frog. Yale J. 
BioI. Med., 1949, 21: 455-462 (with A. Mauro). 85. The Connecticut State Medical Society. Conn. St. med. J., 
1949, 13: 950-955. 1950 
86. Electro-metric study of cotton seeds. J. expo ZooI., 1950, 113 : 
201-210. 87. Bioelectrici ty: potential gradients, Pp. 90-94 in Medical 
Physics. Chicago, The Year Book Publishers, Inc., 1950. 1952 
88. Electro-metrics of atypical growth. Yale T. BioI. Med., 1952, 
25: 67-75· APP ENDIX 
1953 
89· Electrical correlates of ovulation in the rhesus monkey. Yale 
J. Biol. Med., 1953, 25: 408-417 (With V. 1. Gott). 1954 
90. Confusion or configuration? The Astronomical League Bul-
letin, 1954, 4: NO·4· 
1955 
91. Certain electrical properties of the slime mould. J. expo Zool., 
1955, 129: 327-342. 92. Response of the slime mould to electric stimulus. Science, 
1955, 122 : 1020-1021 (with William Seifriz). 1956 
93. Effect of a severe storm on electric properties of a tree and 
the earth. Science, 1956, 124: 1204-1205.
333048200-Harold-Saxton-Burr-Blueprint-for-Immortality-Electric-Patterns-of-Life-OCR-pdf.txt
Summarize the following text section accurately and concisely. Maintain specific details and numerical information, and use anti-repetition mechanisms:

        Sometimes the air and 
earth potentials temporarily go 180 degrees out of phase with 
each other. Examples of these can be seen in Figure 1-
In summary, it is seen that the electrical environment correl­
ates with tree potentials while the more obvious meteorological 
parameters such as light, temperature, and pressure do not in any 
immediate sense. 3 
The absolute range of Burr's tree potentials is 0 to 500 milli­
volts. Sign is arbitrary and defined initially by Burr making the 
upper electrode positive. Polarity can reverse with changes in 
season or large perturbations in potential. Typical values until 
1963 were 20 to 100 mY, and subsequen tly 200 to 400 mv. The 
reason for this increase is unknown. The most obvious characteristic of tree potential records is a 
diurnal cycle, easily seen by inspection. This cycle is typically a 
minimum in the early morning hours and a maximum during 
the afternoon. It may vary in magnitude and in phase from day 
to day, while larger magnitude and phase differences are apparent 
from season to season. The range of diurnal variation of tree potentials during the 
winter months is two or three times that of the summer. The 
magnitude of tree potentials shows a yearly cycle, a minimum in 
April, a maximum in September (see Figure 2). In considering the 
significance of maxima and minima it is necessary to recall that 
the upper electrode was arbitrarily assigned to be positive. So in 
essence the seasonal (yearly) cycle shows two inflection points 
around the time of the equinoxes. Burr believed he could detect a monthly periodicity in tree 
potentials related to phase of the moon. Confirmation of the 
validity of this finding awaited more extensive statistical analy sis 
\vhich will be discussed later in this report. Analysis of all reduced data (a 15-year period) suggests that the 
tree potentials are in phase with the sunspot cycle (see Figure 3). 170 +10r----r--�----�--_r----r_--_r--_,----. _ ·--�----�--_ 
+5 
,. > 
5 0 
-10. J F M A M " 
I \ I 
I \ I I � 
I \ \ I Mon thly Ave. I " 
3-Month Running 
Mean 
J J A S 0 
Months 
Figure 2. Tree potential monthly averages (1946-1961). +50 200 
+40 180 
+30 160 
+20 140 
�. 0 
+10 g 120 
z 
,. > o � 100 E. " " 
80 -10 <II. -20 � 60 
-30 40 
-40 20 Sunspots 
Potential 
Smoothed 
_ 50 0 L--'---'--'-. ". '-- '--. L. - '-'---'---'- ----1--'_'-.
0 to 500 millivolts.
What is the range of Burr's tree potential readings?
To investigate the relationship between magnetic activity and tree potentials.
What is the purpose of using the Ap index in the analysis?
To investigate the relationship between tree potentials and environmental factors, including solar and lunar cycles.
What is the primary goal of the study presented in the passage?
These harmonics may indicate a semi-monthly tidal mechanism.
What is the significance of the 2nd and 4th harmonics in the tree potential spectrum?
The tree was dying and had to be cut down.
Why was the study of the maple tree's records discontinued?