70 



Mr. F. A. Dixey. 



[Nov. 25, 



of tliis part of the cap from a thin layer of bone, pp, which is closely 

 adherent to the cartilage ; in the interval a large blood-vessel is seen 

 cut across, and a smaller branch runs up towards i, which is near the 

 point where the osteoblastic irruption will in all probability begin. 

 Other blood-vessels are seen at hv. This section represents very nearly 

 the same stage in ossification as fig. 2. 



[Magnified about 85 diameters.] 

 Figure 4. Sagittal section through the last two phalanges of the middle digit of the 

 manus of Proteus anguimis. c, unaltered cartilage ; cc, cartilage 

 calcified, but exhibiting no other change. In the terminal phalanx the 

 distal extremity of the cartilaginous core is seen to be narrowed down 

 to a single row of cells with the intervening matrix, p, subperiosteal cap 

 of bone, b, cylinder or dice-box of bone enveloping the shaft of the 

 penultimate phalanx. I, I, lacunae, j, interphalangeal joint, et, ft, ex- 

 tensor and flexor tendons. This specimen was stained with magenta, 

 but not decalcified, for which reason the bony tissue appears light and 

 transparent, instead of being deeply stained, as in the preceding figures. 

 The permanently calcified cartilage shows no alteration in the arrange- 

 ment or size of the cells, which in this instance are remarkably large and 

 regular in form. The animal was believed to be fully adult. 



[Magnified about 85 diameters.] 



(Received October 27, 1880.) 



The fact that the process of ossification in the terminal phalanges 

 begins at the distal extremity, and advances towards the base, has 

 been observed as regards the human foetus, by M.M. Rambaud and 

 Renault (" Origine et Developpement des Os," Paris, 1864). After 

 describing the order in which the first and second rows of phalanges 

 are ossified in the hand, they continue, " De meme pour les troisiemes, 

 ou elle (i.e., l'ossification) debute par le rebord ungueal " (p. 214). 

 In speaking of the foot, their language is more explicit, " Les 

 troisiemes phalanges commencent a s'ossifier par l'extremite anterieure, 

 puis de la l'ossification s'etend vers l'extremite posterieure, laissant 

 toujours un appendice cartilagineux qui se transforme en epipbyse " 

 (p. 240). These authors, however, make no attempt to describe the 

 process, nor to determine how far it is participated in by the cartilage 

 and the superiosteal membrane respectively ; neither do they mention 

 the ungual expansion, or the enveloping cap. Moreover, the statements 

 already quoted from the text of their work are entirely ignored in the 

 plates, where in every figure that contains a representation of growing 

 phalanges, and even in the figures especially referred to as illustrative 

 of the above-quoted statements, the terminal phalanx is made to ex- 

 hibit no difference whatever from the rest in its mode of ossification. 

 For instance, in Plate XXI, fig. 1, it is drawn with a very evident 

 cartilaginous head at each extremity ; yet this figure, in the words of 

 the authors themselves, " represente exactement l'etat de l'ossification 

 de la main a la naissance." (Ibid., p. 215.) 



