Blood-corpuscles of A. tridactylum, dtc. By Dr. Schmidt. 115 
of Man possesses not only a certain inherent power of contracting 
its body, but also of resuming its original form by a subsequent 
expansion, a characteristic property of the living protoplasm, 
enabling the coloured corpuscle to manifest spontaneous motions, 
though not to so great an extent as is seen in the colourless. 
And, furthermore, keeping in mind this inherent property, a part 
of the difficulty hitherto encountered in tracing those various 
spontaneous changes occurring in the form of these bodies to 
their cause, will be removed. 
Nevertheless, as these changes are not only observed to occur 
in different localities of the same preparation of blood, and under 
different circumstances, but moreover are observed to occur in a 
greater or lesser degree in different specimens of blood, when taken 
at different times from the same individual, much doubt will still 
remain as to the true cause of the phenomenon, and the condi- 
tions under which it is manifested. The question therefore arises : 
Do these changes of form indicate progression and development 
and a high degree of vitality residing in those blood-corpuscles 
exhibiting them ; or are they resulting from a loss of vitality, and 
therefore manifestations of retrogression and decay ? In the one 
case, then, they would probably occur on the young, in the other 
on the old corpuscle. 
Without pretending to solve this difficult question, I shall 
venture a few remarks relating to it. If, namely, the changes 
affecting the form of the coloured blood-corpuscle, and evidently 
caused by a contraction of its protoplasm, were indicative of a 
higher degree of vitality or molecular action, we should meet with 
a greater number of mulberry and thorn-apple shaped, or otherwise 
deformed corpuscles in the fresh blood. But as, on the contrary, 
the number of these forms is comparatively small, immediately after 
the blood is removed from the living tissues, and, moreover, increases 
sometimes quite rapidly in proportion to the length of time inter- 
vening, it appears more probable that these changes of form indicate 
retrogression, and we may be justified in regarding them as the 
result of the last vital action manifested by the blood-corpuscle, 
and portending its death. 
In proof of the absence of an enveloping membrane in the 
coloured blood-corpuscles of the Amphibia as well as of Man, it has 
been asserted that they will run into and fuse with each other by 
mutual pressure. It appears to me strange that such a coarse 
error should ever have been committed ; for these bodies never 
run into each other unless they are forcibly crushed into a structure- 
less mass. Even in such a manner it is difficult to destroy their 
individuality, as I shall presently show. It is true that when a 
drop of blood is spread upon a glass slide, the coloured corpuscles 
will by mutual pressure become more or less distorted in shape in 
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