DR. MARTIN BARRY ON THE CORPUSCLES OF THE BLOOD. 233 



150. Figs. 123, 124 and 125, present portions of this nerve in a more or less 

 incipient state. The objects represented, chiefly in outline, in fig. 123, observed at 

 a part of the nerve near its entrance into the eye-ball, were all corpuscles having the 

 same appearance essentially as corpuscles circulating in the blood. I refer for a par- 

 ticular description of these to the explanation of the Plates. The nerve did not 

 present any fibres ; and so incipient was it, that at the part represented in the figure, 

 the corpuscles had their original elliptical form. In another instance, where the 

 nerve was rather more advanced, the globules surrounding the nucleus (see the 

 corpuscle more finished in delineation than the rest in fig. 123.), had very much 

 disappeared, and the corpuscles were pressed into polyhedral forms. 



151. In a former page, I mentioned that the foundation of cartilage had presented 

 an appearance, suggesting, from the more advanced state of the interior, that cor- 

 puscles had been added at the outer part. Such an appearance is even more remark- 

 able in the optic nerve, as shown in fig. 124 ; all the objects in which (presenting, it 

 will be seen, very different states) were observed in the same nerve. I have stated 

 that the corpuscles in fig. 123. had essentially the same appearance as that of cor- 

 puscles of the blood. Respecting those at a, in fig. 124, it may be said that their 

 appearance was precisely such as that of corpuscles circulating in the blood of the 

 same larva. Yet the interior of the nerve in this instance was in a more forward 

 state than that of the one before referred to (fig. 123.) ; the other objects in fig. 124. 

 having been composed of discs (some of them forming necklace-like objects, or 

 incipient fibres), derived from the nuclei of corpuscles, such as those just men- 

 tioned (a). These discs were all red ; the colour being paler in the more advanced. 

 (See the figure and the minute explanation of it.) 



152. Portions of this nerve, in a more advanced state, are seen in fig. 125. The 

 discs at a, into which the nuclei of the corpuscles had divided, were arranging them- 

 selves in something like lines. They presented minuter discs in their interior, as in 

 the part represented less in outline than the rest. The tube |3, yet more advanced, 

 was forming out of discs, which were coalescing at its periphery. These discs, cor- 

 responding apparently to the minutest of those at a, again, presented other discs in 

 their interior. Pellucid points, apparently orifices, were seen here and there. They 

 seemed to communicate with the exterior of the tube (pars. 130, 162, 178.). These 

 pellucid points correspond to the depressions in the original discs. As in muscle, 

 there are doubtless in the interior of an object such as |3, the elements of new sub- 

 stance, — the essential portion of the nerve. 



153. In these researches, a considerable share of my attention has been devoted to 

 the elements of the retina ; which afforded ample proof of their origin in corpuscles, 

 having the same appearance as corpuscles of the blood. Some of these elements are 

 represented in figs. 126 to 131 ; and it will be seen that they are of the same character, 

 whether taken from the foetal Calf, fig. 130, or from the Tadpole, fig. 131 ; consisting, 

 in both, of round, flattish masses of discs. 



