Blood-corpuscles of A. iridactylum, (&c. By Dr. Schmidt. 99 
body, with a clear border, limited by a fine though very distinct 
contour. The inner contour of the apparent wall is, as in the pre- 
I ceding form, represented by the outlines of the zone of granules, 
which here, however, is of greater breadth ; while the outlines of 
the individual granules are considerably darker ; the greenish tint 
of the zone is also more decided. There are no large granules nor 
a nucleus observed in the interior, though it may be supposed that 
they exist, but are hidden by the dark-bordered granules. The 
lighter tint of the body at its centre, compared with that at the 
j periphery, is, of course, due to the difference of refraction existing 
in the rays of light passing through the body, the central rays being 
I less refracted than those nearer the periphery. The third form 
I (c), still larger than the preceding, encloses a distinct and perfect 
I nucleus. The interior of the body appears to be completely filled 
with the dark-bordered granules of a now very decidedly greenish 
tint. When treated with water, these granules become very 
[ distinct, while those of the nucleus are dissolved, and the space 
occupied by the latter is rendered clear {d). Fig. 40, e, represents, 
lastly, a young coloured blood-corpuscle of an oval form and 
greenish tint. Though the nucleus contains a number of granules, 
it will be observed that the dark-bordered granules of the proto- 
plasm have disappeared. 
In examining the forms a, h, and c, it becomes obvious that 
they represent only different stages of development of one and the 
same body. But the question now arises, whether they began their 
development from a perfect colourless blood-corpuscle, or from a free 
nucleus. If developed from a colourless blood-corpuscle, that is 
from a nucleus, surrounded by a layer of protoplasm, the first step 
of the process must be a contraction of the latter upon the nucleus, 
and a condensation of its outer surface, which is shown by the 
even and distinct dark contour, represented in the drawing. The 
I nucleus, of course, would at a somewhat later period assume an oval 
I form, in order to represent that of the future coloured blood-cor- 
! puscle. In the course of development, the whole body would 
enlarge by the formation of new granules, and finally assume an 
oval form; at the same time the granules would disappear, and 
I the greenish tint be changed into the yellowish colour of the 
I mature coloured corpuscle. In regard to the greenish tint, we 
j might ask, whether it is not due to the incipient formation of the 
haemoglobin ? 
! If, on the other hand, these forms arise from a free nucleus un- 
covered by protoplasm, the process must appear more complex ; 
for then the granules would have primarily to be formed in the 
j interior of the nucleus, and deposited upon the interior surface of 
its wall, while a new nucleus is developed from one of the granules 
of the old one. 
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