280 JOURNAL OF CoMPARATIVE NEUROLOGY. 
dergo mitotic division, or whether some of the cells only have 
this power, is not definitely known. If the latter supposition 
is true, then the real relations of these cells to the remaining 
part of the ectodermal cells must be one of the important sub- 
jects to be investigated. It has been claimed by His that the 
germinal cells are fundamentally different from the rest of the 
epithelial cells. This idea of His, however, has been opposed 
by many investigators (von KOLLIKER,’ VIGNAL, SCHAPER,’ etc.) 
SCHAPER has reached the same conclusion as voN KOLLIKER, 
urging that the germinal cells are really young proliferating 
forms of epithelial cells which first gave rise to indifferent cells. 
These latter may be further differentiated, either into nerve cells 
or into glia cells. 
On the assumption that the germinal cells produce two 
kinds of tissues, either nerve cells or glia cells, the primitive 
form of these two kinds of cells has been named by His 
neuroblasts and spongioblasts respectively. The early differ- 
entiation of these cells will not be discussed by this paper. The 
observations here recorded apply exclusively to well character- 
ized germinal cells. 
The germinal cells of the cerebellar cortex of foetal cats, 
present a very characteristic appearance with their circular out- 
line, and well stained chromosomes. The size of the cell-body 
is variable according to the phase of nuclear change which is 
exhibited. The measurements of the cell-bodies will be given 
in the descriptions of the several phases. 
The various phases of the germinal cells in their develop- 
ment may be described advantageously in the following order: 
A. Germinal Cell in the Prophase. In the earliest stage 
of this phase (Fig. 1), the germinal cells assume a nearly spher- 
ical shape. The cell-body*® enlarges slightly, measuring from 
1 Von K6LLIKER: Handbuch der Gewebelehre des Menschen, Bd. II, ’96. 
2 Scuaper, A.: Die friihesten Differenzirungsvorginge im Centralnerven- 
system; Kritische Studie und Versuch einer Geschichte der Entwicklung ner- 
vésen Substanz. Arch. f. Entwicklungsmechn. d. Organ. Bd. V,’97. 
3 There occurs considerable variation of the size of the cell-body as well as 
nuclear area, in each phase. The present investigation applies exclusively to 
the cells of large size. 
