54(i RECORD OF CURRENT RESEARCHES RELATING TO 



Division of Cartilage Cells.* — In a short paper en this snbjtc 

 Dr. W. Bigclow states his disagreement with Butschli's view that the 

 division of the cell-body always goes hand in hand with that of the 

 nucleus, and that the common case of a single cell with two nuclei is 

 not an instance of commencing division. Bigelow's observations 

 on the cartilage of all classes of Vertebrata lead him to the opinion 

 that division of the nucleus always precedes that of the cell-body. He 

 finds, in fact, cells with constricted (biscuit-shaped) nuclei, cells with 

 two nuclei which are considerably larger than the neighbouring uni- 

 nucleate cells, cells with two nuclei and a faint partition wall. In no 

 case was a septum seen before the division of the nucleus was com- 

 pleted. 



Amongst the ordinary cartilage cells of the sclerotic of amphibia 

 and fishes were found some of especially large size, separated from 

 surrounding cells by a great thickness of ground substance, which 

 often exhibited concentric striation, and was stained with gold chloride. 

 They often contained two or three nuclei, and were of very irregular 

 form. Their protoplasm was stained red with gold chloride, instead of 

 bluish like the other cells. The surrounding cells were often arranged 

 radially around these large cells, of the origin and significance of which 

 the author proposes to treat in a future communication. 



Final Changes in Meckel's Cartilage.f — The process of retro- 

 gressive metamorphosis undergone by Meckel's cartilage in mammals 

 has been studied in the pig by Dr. Baumiiller, of \\ lirzburg, who sums 

 up his results as follows : — 



After previous calcification of its intercellular substance, the pos- 

 terior portion of the cartilage undergoes degeneration by fibrous 

 metaplasis, this process extending from the tympanic cavity to about 

 the middle of the alveolar portion of the mandible. Next, an increase 

 in size of the hinder half of the remaining part takes place, connected 

 with changes of form produced chiefly by the growth of the man- 

 dible. The most important of these changes are the constricting off 

 of small pieces, which, enclosed by the lower jaw, contribute to its 

 increase in size, by their subsequent ossification. 



The second step in degeneration consists in the ossification of the 

 remainder of the cartilage, with the exception of the symphysis, where, 

 finally, the same process of fibrous metaplasis takes place, to which 

 the disappearance of the hinder part of the cartilage was due. 



Histology of Nerve-fibre.|— B. Rawitz comes to the conclusion 

 that the constrictions observed by Eauvier are formed, in the living or- 

 ganism, by a circle of pale substance, which surrounds the axis-cylinder 

 and destroys the continuity of the medulla ; that the " double contour " 

 represents the whole of the medullary sheath, but is not to be made 

 out in the fresh state ; it surrounds the axis-cylinder. The crimped 

 appearance observed by Lautermann is due to the breaking up of the 

 nerve- fibre. 



* 'Arch. f. Mikr. Anat.,' xvi. (1879) p. 458. 



t 'Zeitschr. wis8. Zool.,' xxxii. (1879) p. 466. 



I 'Arch. f. Ariat; (Mis and Biaiine), (1879) p. 57. 



