418 TRANSACTIONS OF THE CANADIAN INSTITUTE. [Vou VI. 
II.—THE DEVELOPMENT OF NERVE CELLS WITH SPECIAL REFER- 
ENCE To THE DEVELOPMENT OF THE CHROMATIC 
SUBSTANCE OF THE CELL Bopvy. 
Several attempts have been made to determine the origin of the 
Nissl granules, but all have failed to detect it. Was made some inter- 
esting observations on the chromatin of foetal sympathetic ganglion 
cells but did not attempt to ascertain the origin of the chromatic sub- 
stance of the cell body. Eve found the chromatic substance completely 
filled the cell body at an early date. The cells of the vagus ganglion 
were the first to show an appearance like the adult cell with regard to 
the distribution of this substance. Szczawinska, working with selachian 
embryos, did not trace it further than the stage in which the cells were 
uniformly stained. Buhler” states that foetal cells are devoid of 
granules, but does not ascertain the origin of the granular substance. 
He did, however, notice that the nuclei of young nerve cells are baso- 
phile and gradually become oxyphile as development proceeds. Timo- 
feew observed that in chick embryos the basophile substance increased 
markedly in amount in the cells of the spinal ganglia, between the fourth 
and sixth day of incubation. He says nothing of its origin and evidently 
considers it cytoplasmic. 
The chromatic substance which forms the Nissl granules is undoubt- 
edly derived from the nuclear chromatin. A series of pig embryos from 
7mm. onward to birth was the chief material used for these obser- 
vations, but calf, sheep, rabbit and chicken embryos were used to 
confirm the results. 
The embryos were fixed in the bichloride-bichromate mixture or in 
picro-corrosive fluid. Material intended for chemical methods was fixed 
in alcohol. 
The development of the chromatic substance which forms the Nissl 
granules is closely connected with the morphological development of the 
cell. His® showed that the neuroblasts are derived from cells, lying, in 
mammals, next the medullary canal, which he calls germinating cells. 
These cells have a protoplasm which may be divided into an outer clear 
2) oenCi pada Os 
53 His, W., ‘‘Die Neuroklasten und deren Entstehung im embryonalen Mark,” Arch, f. Anat. u. 
Phys., Anat. Abth., 1889, p. 249. 
Also, ‘‘ Histogenese und Zusammenhang der Nervenelemente,’’ Arch. f. Anat, u. Phys., Supp. 1890, 
P. 95: 
hoon 
