234 
DR. MARTIN BARRY ON THE CORPUSCLES OF THE BLOOD. 
154. Here also, corpuscles having the same appearance as young corpuscles of the 
blood, become orange-shaped, present two or more bright points with red colouring 
matter between them (see the figures) ; and, as the colouring matter disappears, 
admit of being traced into the masses of discs just mentioned ; these being the altered 
nuclei of the corpuscles in question. We thus find in the elements of the retina, as 
well as in those of cellular tissue (par. 134.), the same appearances as those presented 
in the formation of pus-globules out of corpuscles of the blood. 
155. After the corpuscle, having the same appearance as corpuscles of the blood, 
has become a mass of discs, the discs may undergo division and subdivision to an 
inconceivable extent, and to which we can set no bounds, as regards either the 
number or the minuteness of the resulting objects. It will be observed, from fig. 130, 
that cells are formed ; their membranes arising — as elsewhere, according to my ob- 
servations — from the coalescence of minute discs. These cells will be found minutely 
described in the explanation separately given. It is not my purpose in this memoir 
to follow their subsequent progress. 
156. I have frequently met with the rudiment of the spinal chord, — sometimes in 
fragments, sometimes almost entire, — as it exists in the tail of the Tadpole ; this 
larva measuring 5'" or 5 Its newest part I found composed entirely of corpuscles 
having essentially the same appearance as corpuscles of the blood, and being in a 
state resembling (but somewhat more advanced than) that which they presented in 
the optic nerve fig. 124 a, and also arranged in lines. In fig. 132. is an outline of 
some of the corpuscles which I observed constituting this structure in a Tadpole of 
5^"'. The spinal chord has uniformly appeared to be less advanced than the cellular 
tissue which seemed to be entering into the formation of its sheath (par. 136.). 
157- Corpuscles from the cortical substance of the brain in a foetal Calf of 5| 
inches, are seen in fig. 133 : and fig. 134. represents some of those observed in the 
medullary part of this organ, in the same subject. 
158. Objects such as those in the first of these two figures, were observed in large 
number ; and often seen to be flattish in their form. They were all more or less 
red, — some blood-red ; all were either discs, or composed of discs, — being either 
themselves corpuscles, having the same appearance as corpuscles of the blood, or 
immediately derived from such corpuscles. Here, as often observed in other parts 
in the course of formation, the corpuscles were found to be of a minute size ; being 
apparently young corpuscles. They presented the same gradual transition into the 
elements of the brain, as we have seen in other parts, regarding a change in form, 
colour, and division into discs ; besides the previous appearance of an orifice ((3), in 
the situation of the depression presented by the corpuscle when discoid in its form. 
The gradual formation of a membrane too, by coalescence of the outer discs, was 
witnessed here (q). These details will be found more fully given in the explanation 
of the Plates. And perhaps there is no figure more instructive, as regards the changes 
