Hatat, Mitosis in Nerve Cells. 295 
Cajav! classified the nucleus of the nerve cells in three 
large groups. The third type of the nucleus, according to him, 
is noticeable among the large nerve cells; motor neurones, 
spinal ganglion cells, cells of PURKINJE, giant pyramidal cells, 
etc. In these classes of cells, the nucleus is pale, containing 
the nuclear sap and traversed by a network in which the knobs 
never carry the chromatic granules. The chromatic granules 
concentrate themselves surrounding the single voluminous nu- 
cleolus and form a perfect spherule. Although his description 
is not universally applicable, the present writer has observed 
very often such nuclei as those described by Cajat in the large 
somatochrome cells. In these nuclei the basophile granules 
centralize themselves, surrounding the nucleolus, thus forming 
compact spherical masses composed of acidophile and basophile 
substances. This fact offers a very favorable opportunity to 
determine whether the basophile granules which surround the 
acidophile substance of the nucleolus can be regarded as one 
of the structural parts of the latter organ, because in such 
cases, if Lrvi’s statement is right, how can we distinguish the 
basophile particles which were regarded by him as one of the 
structural parts of the nucleoli from the other part of the baso- 
phile? It is impossible to distinguish these, since they are 
nothing more than degrees of centralization of chromatic gran- 
ules. The present writer therefore concludes that the nucleolus 
is a group of the acidophile particles which is surrounded by 
the linin. 
VII. Summary. 
In the cerebellar cortex of the foetal cat, a study of the 
largest germinal cells shows : 
1. The germinal cells of the nervous system of the foetal 
cat present a modified form of the heterotypical mitosis of 
FLEMMING. 
2. The number of the chromosomes represented by inter- 
nodes of segmented filaments is 16. 
1 RAMON Y CAJAL: Loc. cit. 
