282 MEMORANDA, 
Let it not be thought that microscopic particles are unable 
to produce such great and rapid changes. It is well known, 
C) x 400 & ) 
and I have frequently timed it with my class, that a tea- 
spoonful of human saliva will, when shaken with a like 
quantity of decoction of starch, convert the whole of the 
latter into sugar in a little less than one minute. If ptyaline, 
the active principle of saliva, exerts this power at most in a 
few minutes, then surely the active principle of the secretion 
of the serpent’s poison-gland may exert an infinitely greater 
power in as many hours. 
It results, then, that a person dies slowly asphyxiated by 
deprivation of oxygen, in whatever other way the poison may 
also act, and so far as the ordinary examination of the blood 
goes, the post-mortem appearances are similar to those seen 
after drowning and suffocation. 
{I have many reasons for believing that the materies morbi 
of cholera is a nearly allied animal poison. If so, may we 
not hope to know something definite of the poisous of hydro- 
phobia, smallpox, scarlet feyer, and, indeed, of all zymotic 
diseases ? 
