Ossification Process in Birds, &c. By Br. L. Schdney. 73 
more coloured, and get in circulation without a transition from one 
to the other being absolutely necessary. The same objection may 
also be applied to the blood-corpuscles of the mammals. If there 
are in the beginning visible nucleated, and afterwards non-nucleated 
blood-corpuscles, who can prove that the latter originated in the 
former, and that every red blood-corpuscle has passed through 
a stage in which it possessed a nucleus ? * 
Let us contemplate Fig. 6, which represents an oblique section 
of the ossification border of the limb of a growing fowl. "We 
observe in the centre of a secretion space (Aus-schmelzungsraumes) 
(a) homogeneous lustrous small particles, lying in irregular spaces 
which are bounded by spindle-shaped elements, and of which one 
can convince oneself with the aid of the adjusting screw. One is 
further convinced that the little knobs become pointed at the ends 
at least in one direction, and are in no wise connected with already 
formed blood-vessels. These little particles are by writers unani- 
mously declared to be the first vessel formations, which, in mammals 
as well, appear in the centre of each marrow-space, where the 
blood-vessels also gradually disappear in ready-formed marrow- 
spaces. There is no doubt that the small spindles in the section 
belong to vascular endothelia ; but what are the lustrous corpuscles 
in the centre of the marrow-spaces ? 
Bodies lying in the surroundings of unfinished or ready-made 
blood-vessels may indeed be described as blood-corpuscles ; the cor- 
puscles, however, which are before us, are no blood-corpuscles, but 
hamatoblasts only to begin with. They are distinguished, as 
mentioned before, by a homogeneous structure, and a peculiar 
yellowish-greenish lustre. I cannot attribute any very great im- 
portance to the colour itself, because the parts which have lime 
deposited in them too have a yellowish-greenish lustre, whilst the 
ready-made blood-corpuscles in my preparations are often wanting 
in this colour. Surprising, however, is it that there are no nuclei 
visible in these corpuscles, and still more so that the blood-vessels 
which lie lower down towards the ready-formed bone, and the con- 
nection of which with older blood-vessels cannot be proved with 
certainty, are brimful with blood-corpuscles which show no nuclei. 
Only in lower vascular formations appear the characteristic, oblong 
nucleated corpuscles of the bird's blood. If it must now be ad- 
mitted that the latest marrow formations must be looked for close 
to the ossification border of the cartilage, the older ones, however 
lower down, and if further in so small a space as, relatively speak- 
ing, the field of some medullary spaces is, are found such manifold 
formations, which must be pronounced as blood-corpuscles, then 
the idea that the nucleus is by no means an early, but, on the 
contrary, a rather late formation in the blood-corpuscle (as besides 
* We think this is clearly proved by reference to the blood of the CameUdoe, — 
Ed. ' M. M. J.' 
