Blood-corpuscles of A. tridactylum^ &c. By Dr, Schmidt. 75 
On many of the blood-corpuscles a number of straight longitudinal 
folds are observed. These disappear again by the continued action 
of the acid vapour, and the wrinkled surface of the corpuscle then 
appears as smooth as before. But in the depth of some of the 
previously existing folds a fine stripe of a pink colour is left, 
appearing to represent a rent or fissure in the contents of the 
corpuscle. 
When the 2 per cent, solution of boracic acid itself is applied to 
the blood-corpuscles, they are rendered pale, and their contents 
appear finely granular, while the double contour becomes very 
distinct. Finally, by the continued action of the acid the granular 
appearance is lost, and they become perfectly clear. The nucleus 
is rendered coarsely granular, and its outlines appear irregular and 
serpentine ; the outer contour of its enveloping membrane is dark, 
while the inner one has become more indistinct (Fig. 28). 
Exposed to the action of the vapour of a 4 per cent, solution 
of osmic acid for about five minutes, the blood-corpuscles are 
rendered paler, almost colourless. Their double contour appears 
somewhat more distinct than in their fresh condition. The nucleus 
remains almost unchanged. In some cases its outline and granules 
become more distinct. But while perhaps the greater portion of 
the blood-corpuscles remain unaltered in form, a number of smooth 
wrinkles running mostly in a longitudinal direction are observed on 
others. Some of these latter have assumed a dish-like form, the 
nucleus projecting on the convex surface (Fig. 29). 
In exposing the coloured blood-corpuscles to the vapour of a 
solution of osmic acid of only 2 per cent, for about two or three 
minutes, the above-mentioned changes do not occur, but the 
corpuscles remain almost entirely unaltered in appearance. For 
this reason E. Kay Lankester, in his article “ On the Red Blood- 
corpuscle ” mentioned in the beginning of this paper, recommended 
the vapour of a solution of osmic acid as the best agent for the 
preservation of these bodies. I can endorse his recommendation ; 
for a number of specimens of the blood of the Amphiuma and the 
Frog, prepared in this manner and mounted in glycerine instead of 
in a nearly saturated solution of acetate of potassa more than three 
years ago, show hardly any alteration up to this time. Previously 
to employing the glycerine, I had made use of the solution of 
acetate of potassa, but found it rendered the blood-corpuscles very 
indistinct in quite a short time. 
In exposing a specimen of blood of the Amphiuma to the 
action of the vapour of a 50 per cent, solution of the hydrate of 
chloral for about two minutes, a portion of the coloured corpuscles 
are rendered paler without alteration of their form, while others 
are wrinkled in a longitudinal direction. In a third portion, how- 
over, the protoplasm is observed to contract in the form of an 
