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



part of the foundation of the orbit. They are in outline only ; the nuclei 

 rather more finished. The latter presented discs, a. The cell con- 

 tained two nuclei, besides discoid objects. The former and a few of 

 the latter are represented in the figure. These discoid objects probably 

 resulted from decomposition of the outer part of one of the nuclei, — 

 thus rendered smaller than the other. (The contents of the other cells 

 are not represented in the figure.) (Essentially the same state observed 

 in the foundation of a vertebra, in a Tadpole of 7'".) 



Fig. 119. Common Fowl ; chick in ovo, on the tenth day of incubation. Elements 

 of cartilage. (Foundation of a bone — diameter y" — in one of the 

 lower extremities.) Partly in outline. Red colouring matter still pre- 

 sent in the objects (3 ; which, however, were paler than the objects a. 

 Those at )3 formed a dense mass. (Portions of incipient vertebrae seen 

 in a similar state from the same chick (fig. 122.) ; substance also from 

 the extremity of a duck's bill, and from its claw (thirteenth day of incu- 

 bation), observed to be in essentially the same state, and with a cor- 

 responding transition out of corpuscles, having the same appearance 

 as corpuscles of the blood.) 



Fig. 120. From the same object as fig. 119. Appearance, chiefly in outline, of the 

 marginal portion. 



Fig. 121. Tadpole, 5'". Portion of the cartilaginous foundation of one of the orbits; 

 composed of the nuclei of corpuscles, resembling corpuscles of the 

 blood. Colour red. 



Fig. 122. Objects from the foundation of a transverse process of one of the vertebrae 

 in the chick from which fig. 119. was taken, a. Blood-red corpuscles 

 composed of two or three discs. They resembled altered young blood- 

 corpuscles. These appeared to be entering into the formation of the 

 cortical portion of the transverse process, in which objects such as 

 those at j3 occupied a less superficial place. 



PLATE XXIII. 



Fig. 123. Tadpole, 4 J'". Outline of corpuscles having essentially the same ap- 

 pearance as blood- corpuscles, collected to form the optic nerve. Taken 

 from a part of the nerve, just before its entrance into the eye-ball, 

 which part measured in diameter about ■^'". One of the corpuscles is 

 not merely in outline ; the peripheral part being represented in a more 

 finished state. The central portion however — nucleus — is not shown. 

 At the periphery are seen minute, highly refracting, red discs, dividing 

 into minuter discs. The nerve did not present any fibres, the corpuscles 

 being merely in contact with one another. In another instance, where 



