Anatomy. — "Av the post-embrtjonic gromth of the nervous sijsteni 

 due only to an increase in size or also to an increase in 

 number of the neurones:" (Second part). By Erik Agduhr. 

 (Communicated by Prof. J. Boeke). 



(Communicated in the meeting of February 22, 1919.) 



Mitoses. 



In connection with these matters I have found specially interesting 

 phenomena in the thoracic region of a puppy seventeen days old. The 

 spinal ganglia were tixed according to Flemming's method, cut up in 

 paiaffin sections from 3 /i to 5 f« thick and stained with the iron 

 alum liematoxilin of Heidenhain. in these continuous series of sections 

 I found a large number of mitoses — an approximate calculation 

 showed that in a single one of these ganglia there were oxer two 

 hundred mitoses. Figures 5, 6, 7, and 8 show how these mitoses appear 

 in the preparation. One would be inclined at first sight to refer these 

 mitoses, especially the ones reproduced in figures 5 and ii, to the 

 large ganglion cells — the light field round the chromatin showing, 

 of course, a rather difï'use ti-ansition to the rest of the protoplasm. 

 Owing to the continuous series I was able, howevei', to follow the 

 cells from one section to the other, and then I found that the real 

 nuclei of these ganglion cells weie not found in a stage of division, 

 and that these mitoses must belong either to other small cells situated 

 betw^een the ganglion cell and its capsule or probably to cells that 

 forni the capsule itself. In fig. 7, on the other hand, merely from 

 the sharp outline which the light field makes against the surrounding 

 protoplasm it is clear that there can be scarcely any question of 

 the existence of a mitosis in the ganglion cell — this was also 

 confirmed by the investigation of the same ganglion cell in the 

 preceding and following sections. In fig. 8 we have again an example 

 of a cell which is going to divide mitotically, and which is situated 

 outside the capsules of the surrounding ganglion cells. With regard 

 to size it resembles most closely the cells in mitotical division in 

 figures 6, 7, and 8, but on closer examination, for instance, if they 

 are traced from section to section, one finds that it is surrounded 

 by capsule cells. We thus seem to be quite justified in describing 



