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influence of the ammonia from the nucleus into the body. 
In some corpuscles I have found that the action had not pro- 
ceeded to this extent, and the nucleus though much swollen 
granulated very sharply (fig. 13 6). In many cases the 
nucleus assumed the colouring matter or hemoglobin, and 
remained pellucid whilst the body became colourless and 
granulated under the influence of the acetic acid (fig. 14 ¢). 
Similar results without much change of shape in the cor- 
puscle were obtained when a weak solution of ammonia was 
allowed to act directly on the corpuscles (fig. 14 c). When 
strong ammonia gas or solution was allowed to act on the 
corpuscles so as to produce the small spherical form, the 
addition of acetic acid caused these small spherical corpuscles 
to burst, and then granulated spherical masses were obtained 
in various parts of the field, due to the fragments of the 
burst corpusles. In one case (fig. 12 4) a corpuscle had 
thrown out two pseudopodial-like processes under the influ- 
ence of the ammonia gas. I watched then the gradual 
working of acetic acid vapour, causing the processes to be 
slowly retracted just as in protoplasmic movement, and after 
a nearly circular outline had been assumed (fig. 12 a’), the 
granulation of the body came on, the nucleus remaining clear. 
The behaviour of these corpuscles under alternate weak 
ammoniacal and acid vapours furnished a very curious 
parallel to the movements of amceboid protoplasm, and a 
careful consideration of the phenomena may throw some 
light on the nature of protoplasmic contractility. 
The second type of form assumed by the frog’s red blood- 
corpuscles under the influence of weak ammoniacal vapour is 
seen in fig. 10a. The red content of the corpuscles, the 
zooid of Briicke, contracts vigorously, and separates itself 
from the cecoid or dense superficial membrane, giving the 
various appearances depicted. This resembles the action of 
boracic acid described by Briicke, except in this, that the red 
matter, the zooid, is in no way granulated, but remains perfectly 
clear and homogeneous. Acetic acid vapour caused to act on 
the corpuscles in this state gives a general granulation of the 
whole of the red mass (fig. 10 4, 4), but no delimitation or 
granulation of a nucleus, which seems to be lost or dissolved. 
In one case, from my notes, I find that weak ammoniacal 
vapour having been allowed to act, some of the corpuscles 
had assumed the form represented in fig. 10 a, with the 
*“ zooid”’ contracted away from the “ cecoid,” others had not 
reached this condition, and contributed but little change of 
form. Acetic acid vapour was now drawn in, the corpuscles 
with the contracted, zooid became granulated in that part, 
. 
2 
