375 
Though a small point, this was left uncertain from Stricker’s 
experiments. 
When human corpuscles are used in place of those of the 
frog, the spherical condition having been first obtained by 
the action of aqueous vapour, Stricker showed that the 
normal biconcave form is obtained by the action of CO,, 
whilst the substitution of atmospheric air causes a more 
spheroidal condition again, and in many cases the “ thorn- 
apple form,” which again yields to the normal’ biconcave 
form on renewal of the CQ, (see figs. 19 a, 6, c,d). The 
alternation can be obtained several times. 
10. Effect of osmic acid vapour.—I have above spoken of 
the use of the vapour of osmic acid. ‘To observe its gradual 
working a drop of the concentrated solution may be placed 
in the gas-chamber, or air drawn into the chamber which has 
been allowed to bubble through a solution. On the human 
corpuscles it has absolutely no visible action, excepting that 
it changes their tint, by acting on the hemoglobin. Although 
the blood becomes set by its action into a jelly-like film, no 
alteration of the form or inner aspect of the corpuscles is pro- 
duced. ‘This was determined by comparison of fresh blood 
and blood acted on by the OsQO, In the frog’s blood- 
corpuscles the nucleus becomes rather sharply defined under 
the influence of the osmic acid vapour, but it is not coarsely 
granulated as by most acids. 
ll. Effect of acetic acid, vapour, and in solution.—If air 
be drawn into the gas-chamber, which has bubbled through 
acetic acid and the corpuscles of the frog exposed to it, the 
following effects are observed. If the solution of the acid be 
weak, so that but very little acts on the corpuscles, the first 
result noted is a “ starring” of the body of the corpuscle and 
the sharp definition of the nucleus (fig. 8a). The strength 
being increased, the nucleus becomes coarsely granulated 
(fig.86). Thestrength being still further increased, so as to 
reach its maximum, the body of the corpuscles becomes 
granulated here and there, and its outline finely irregular 
and thickened ; the plasma at this stage also exhibits a very 
fine molecular precipitate (fig. 8c). When a solution of 
acetic acid is added directly to the blood, the extreme action 
is obtained at once, unless the solution is very dilute (2 per 
cent. of the glacial acid in water) when the earlier conditions 
are obtained. 
- 12. Effect of alcohol—Although the effect of alcohol is to 
produce a precipitation in the corpuscle, yet this is different 
from that produced by acetic acid. Weak vapours of alcohol 
have little effect; stronger cause an irregularity in the out- 
