DR. MARTIN BARRY ON THE CORPUSCLES OF THE BLOOD. 231 



having the same appearance as corpuscles of the blood, not to induce the belief, that 

 it is the blood-corpuscles entering into the formation of the covering of the ovisac, 

 which form the corpus luteum. 



139. As long since as in the autumn of 1838, my friend Dr. Hodgkin mentioned 

 to me a view entertained by him, that the blood sent to the enlarged Graafian vesicle, 

 becomes the corpus luteum. This requires from me no other comment than that 

 afforded by the observation now recorded. 



The Elements of Cartilage and other Tissues compared with Corpuscles of the Blood. 



140. The early stages in the formation of cartilage, which happen to have fallen 

 under my notice, were observed in the foundation of a bone in one of the lower ex- 

 tremities of a foetal chick, on the tenth day of incubation (figs. 119, 120.) ; in the foun- 

 dation of a spinal vertebra from the same chick (fig. 122.) ; in that of one of the cranial 

 vertebrae from a Tadpole of 5'" (fig. 117-) 5 i^ the foundation of the orbit in another 

 Tadpole of the same size (fig. 121.), — this cartilage having been seen in a different 

 state in a Tadpole of 6'" (fig. 118.); and also in an incipient spinal vertebra from one 

 of these larvae. In these observations, a transition out of corpuscles having the same 

 appearance as corpuscles of the blood, was either directly witnessed, or to be inferred. 

 Such corpuscles, generally speaking, are not represented in the figures, because the 

 cartilage was too far advanced. Yet in fig. 117, on the left side, there may be seen 

 two remarkable corpuscles of this kind. The eye becomes so accustomed to the 

 altered nucleus of the corpuscle, having the same appearance as the corpuscle of the 

 blood, that it is scarcely requisite to see that corpuscle in an entire state. In these 

 observations, however, there was not wanting the characteristic red. In fig. 119, for 

 instance, this colour was recognizable after the nuclei had begun to arrange them- 

 selves into fibres ; in fig. 122. the young corpuscles a, situated in the incipient carti- 

 lage of a vertebra, were blood-red ; in fig. 1 17, on the left side, as already mentioned, 

 is the outline of two elliptical corpuscles having the same colour and general appear- 

 ance as the blood-corpuscles circulating in the vessels of the same larva (the Tadpole) ; 

 and the red colour was noticed also in the objects of fig. 121. 



141. It may here be remarked, that the corpuscles which, in the incipient cartilage 

 fig. 1 17, had the same appearance as the blood-corpuscles of the animal, were situated 

 in the most superficial part, as though added to corpuscles previously there. This 

 was the case, also, with the young and red corpuscles a in fig. 122. And we shall 

 hereafter find the same superficial situation to be occupied by the newest corpuscles 

 entering into the formation of the optic nerve (par. 151.). 



142. In examining the foundation of cartilage, the observer is struck with the 

 regularity of distance between the nuclei of the corpuscles ; this being referable, ap- 

 parently, to the presence originally of the entire corpuscles (fig. 117-), the outer part 

 of which afterwards disappears (fig. 121.) ; and a dense mass is formed, by continual 

 additions from the nuclei, as centres for the origin of new substance. It seems to 



