loDenny   and   Minot:      Arch,   Int.   Med.,   1916,   xvii,    101;    Am.   Jour.   Physiol.,    1915,

xxxviii,  233.
"Addis,  T.:     Quart.  Jour.  Med.,  1910,  iv,  14.
12Cannon  and  Mendenhall:     Am.  Jour.  Physiol.,  1914,  xxxiv,  225.
"Howell,  W.  H.:     Arch   Int.  Med.,  1914,  xiii,  80.
"Brodie,  T.  G.:     Jour.  Physiol.,  1897,  xxi,  403.
isWhipple,  G.  H.:     Arch.  Int.  Med,  1912,  ix,  365;  Jour.  Exp.  Med.,  1911,  xiii,  136.
leWhipple,  G.  H.:'    Arch.  Int.  Med.,  1913,  xii,  637..
i?Duke,  W.  W.:     Arch.  Int.  Med.,  1912,  ix,  258.
CHAPTER  XV

BLOOD  PRESSURE

The  object  of  the  circulation  is  to  maintain  through  the  tissues  a  sup-
ply of  blood  that  is  adequate  to  meet  their  demands  for  nutriment  and
oxygen  and  to  remove  the  effete  products  of  their  metabolism.  The  de-
mands vary  according  to  the  activities  of  the  tissue,  being  particularly
variable  in  the  case  of  such  tissues  as  the  muscular  and  the  glandular.
In  studying  the  physiology  of  the  circulation  we  have  therefore  to  bear
in  mind  two  aspects  of  the  problem:  (1)  the  cause  for  the  continuous
bloodflow,  and  (2)  the  mechanism  by  wrhich  alterations  in  this  bloodflow
are  brought  about.
