Blood-corpuscles of A. tridachjlum, &c. By Dr. Schmidt. 63 
to the blootl-corpnscles, I had, for want of a gas chamber, to resort 
to a more primitive method, which, however, answered the purpose 
perfectly. It consisted in placing the slide holding the film of 
fresh blood directly over the open mouth of a bottle containing the 
reagent. After exposing it to the action of the latter, from one- 
half to three minutes, or even longer, it was removed, and quickly 
covered by a plate of thin glass. In examining a number of 
specimens, exposed in this manner to the vapour of the reagent 
for various lengths of time, I was enabled to observe the changes 
taking place gradually in the blood-corpuscles as well, I believe, 
as if the latter had been enclosed in the gas chamber. For, 
whether the film of blood be enclosed in the gas chamber, or laid 
over the open mouth of the bottle holding the reagent, the blood- 
corpuscles will in either case not be affected simultaneously, unless 
the film is very uniform in thickness ; those nearest to the surface 
will, of course, be acted on first. But even under equal external 
conditions, some of the blood-corpuscles seem to be more sensitive 
to the action of a particular reagent than others. The cause 
of this phenomenon must be sought in the peculiar conditions 
of these bodies at the time, such as age, composition, &c. 
The Coloured Blood-corpuscles of Amphiuma tridactylum . — 
These blood-corpuscles resemble in shape and other peculiarities 
those of the Frog and other Amphibia. Each of them represents 
an oval disk (Fig. 1), enclosing an oval nucleus. The diameter 
of the disk ranges in different specimens from to iiim. 
in length, and from ytto to yjoy in width. The mean dia- 
meter of the nucleus is about yfyy mm. in length, and yyyy mm. 
in width. The profile of these blood-corpuscles represents a bi- 
convex disk, the middle portion of which swells out in the form 
of an oval prominence. This prominence, which is formed by the 
nucleus and a portion of the body of the corpuscle covering it, 
measures about y^fo nim. in thickness. The thickness of the 
blood-disk itself, beyond the area of the nucleus, is about y/v^ mm. ; 
it gradually diminishes toward the margin of the disk, where it 
only amounts to yo%o‘ There are no sharp angles presented 
in the outlines of the profile of these blood-corpuscles, as I have 
seen them sometimes erroneously represented in those of the Frog 
and Salamander, where the whole corpuscle resembles a sphere set 
in a disk with a thick round border. On the contrary, the pro- 
minence at the place corresponding to the periphery of the nucleus 
is lost upon the disk in the form of a graceful curve (Fig. 2). 
The very margin of the disk is rounded. The colour of the 
corpuscles is of a dirty yellow with a slightly greenish tint, and in 
the fresh, normal specimen uniform throughout; in the centre, 
over the nucleus, however, they appear colourless. 
In getting the margin of these blood-corpuscles by an accurate 
