Blood-cor^usdes of A. tridaetylum, (&c. By Dr. Schmidt. 107 
than those just discussed are produced by the contraction of the 
protoplasm, and not unfrequently met with in examining specimens 
of blood. Thus, blood-corpuscles with irregular sharp ridges or 
spines, projecting from their surface (Fig, 50), will be observed. 
It must be obvious to the observer that these forms resemble those 
thorn-apple forms which are of quite common occurrence in human 
blood. 
When the coloured blood-corpuscles* of the Frog are treated 
with water, the same phenomena are observed as have been 
described in connection with the blood-corpuscles of the Amphiuma. 
Their colouring matter gradually disappears, until they are rendered 
entirely colourless. But their outlines do not become invisible ; 
on the contrary, they appear now in the form of a delicate double 
contour (Fig. bl, a and h), representing the membraneous layer of 
the blood-corpuscle. In some instances the outlines appear wavy 
or crenated ; of the probable cause of this appearance I have 
attempted to give an explanation in connection with the blood- 
corpuscle of the Amphiuma. As in the case of the latter, the 
granules contained in the nucleus are also dissolved by the action 
of water, while the whole body expands. Treated with a very weak 
solution of chromic acid after having been acted on by water, the 
delicate contour of the blood-corpuscle, as well as that of its 
nucleus, appears at once darker (Fig. 52), while a few granules 
reappear in the latter. 
When the blood-corpuscles of the Frog are exposed to the 
action of the vapour of acetic acid for about one minute, the proto- 
plasm is observed to coagulate in the form of small granules, while 
the membraneous layer, represented by its double contour, remains 
unaltered. At the same time, the former contracts, leaving a clear 
space between itself and the nucleus (Fig. 53). Treated with the 
liquid acetic acid in a diluted form, the blood-corpuscles are 
rendered entirely colourless, but bordered by a delicate double 
contour ; while the nucleus becomes dark bordered. 
Subjected to the action of chloroform vapour for several 
minutes, these blood-corpuscles are discoloured, and their outlines 
rendered very faint, almost invisible. When in this condition they 
are treated with a very weak solution of chromic acid, their outlines 
will reappear in the form of distinct dark double contours, together 
with numerous granules distributed throughout the interior (Fig. 
54, a). In some instances (b and e) a number of these granules 
are observed to be arranged in lines, radiating from the nucleus 
toward the periphery. Sometimes the blood-corpuscle assumes 
the form of a dumb-bell {d). 
The effect produced on the blood-corpuscles of the Frog by the 
action of a strong solution of hydrated chloral, differs somewhat 
from that observed on these bodies in the blood of the Amphiuma. 
