art. 2. At Newcastle, and in Cumberland, it is popularly known by the
name of Water-jags. See Dr. Wood, in the Med. and Phys. Journal,
vol. xiii. p. 58. note,

* See his paper in the Med. Transact, of the Coll. of Phys. vol. i.
art. xvii.
•f " Varioke pusilla,^* See his Comment, de Morbis, cap. 96.
:(; See Vogel, de cognoscend. et cur. Horn. Morb. } 128. (edit. 1772).
Burserius, Inst. Med. vol.ii. cap. 9. J 305. Sauvages, however, actually
makes it a species of Variola, class, iii. gen. ii. spec.i. V. lymphatica,

s 2



260 vESicuLJE :

gone Smallpox: 4, that tlie shades of difference
between modified Smallpox and Chicken-pox were
so indistinct as to render the diagnosis almost impos-
sible/' Thus Dr. Thomson has remarked that the
Variola, in its undoubted form, and Varicella, appear
under the same exciting causes, whether the persons
have been vaccinated or not : thence he concludes that
they are merely varieties of the same disease. He also
affiims that persons exposed to the contagion of Va-
ricella have had Variola, and that Varicella never ap-
pears in those whose constitutions have been modified
by previous Variola. " The first of his positions has
been refuted by the appearance of Varicella as an
epidemic without Smallpox existing in Copenhagen,
in 1 809 and several years afterwards.'* * But I believe
vesicular Varicella has never been communicated by
inoculation ; that children have Chicken-pox in the
mildest form who have had Smallpox, or who after-
wards take it. One might understand how Smallpox
occurring a second time might be modified into
Chicken-pox : but, if the majority of children have
Chicken-pox in the mild form, under all circumstances^
I cannot accord in the opinion of Dr. Thomson.
