Blood-corpuscles of A. tridactylum, dec. By Dr. Schmidt. 113 
unaltered ones in the centre of the preparation, immediately or 
soon after the blood is placed on the slide. Soon after, other 
individual corpuscles are seen to assume these forms, the number 
increasing with the time, until finally whole groups or the entire 
mass may undergo this change. In other instances, considerable 
portions of the blood-corpuscles of the preparation may, soon after 
the blood is put upon vthe slide, contract at once, and assume the 
thorn-apple form, appearing almost as if afiected by a general 
contagion. The thorn-apple form may even be produced by the 
action of water, as I have observed. The form of the blood-cor- 
puscle, when gradually and slowly undergoing these changes, seems 
to pass through several phases. The first deviation from the 
original form observed, consists in minute elevations or protuber- 
ances, arising from the surface of the corpuscle at its rounded 
margin, thence, while increasing in number, extending over the 
entire corpuscle. Next, the protuberances, at first of a conical 
form, become gradually smaller in diameter at their base, while 
their points or summits enlarge to assume the form of a knob, 
resembling a granule. It is at this stage of the change that the 
form of the blood-corpuscle has been compared to that of a mul- 
berry. As the change continues, the globular projections become 
thinner, until finally they are transformed into minute, sharp 
spinous processes. In this state the blood- corpuscle resembles a 
thorn-apple. But it is not necessary that, when the change of 
form has once set in, it should pass through all the stages to the 
ultimate thorn-apple form ; on the contrary, the contraction may 
cease at any stage of the process, or even cause at once the mul- 
berry or thorn-apple form. Yery little alteration in the general 
form of the corpuscle is observed to take place by this process ; it 
is not rendered spherical, as might he supposed, but represents still 
a disk, though the concavities may have disappeared from its surfaces, 
or even be converted into convexities. 
In the beginning of this paper, when describing the changes 
observed to occur in the form of the fresh giant blood-corpuscles 
of Amphiuma tridactylum, I related an instance (Fig. II) in 
which I distinctly observed a spontaneous expansion and contrac- 
tion occurring in one of these bodies. This was the only case of 
spontaneous motion I ever met with in the blood of the Amphibia, 
though in the coloured blood-corpuscles of Man 1 had witnessed 
this phenomenon as early as in the summer of 1871. In examining 
a specimen of human blood, and whilst my attention was directed 
to the coloured corpuscles as they were carried along by a moderate 
current of the liquor sanguinis under the covering glass, I noticed 
on some of them the projection and immediate withdrawal of 
minute, conical, thorn-like processes (Fig. 61, a), whenever one 
blood-corpuscle came into the vicinity of another, without, how- 
VOL. I. K 
