47 2 
MONTGOMERY. 
[Vol. XV. 
which is nearest to the wall of the acinus, i.e ., nearest to the 
source of the food supply ; only then does it come to occupy a 
central position within the cell, when the latter has attained its 
maximum size and the thickness of the cell membrane shows 
that the cell is assimilating little or no nourishment from 
without. 1 
b. Somatic Cells. 
12 . Ganglion Cells of Do to. 
(Plate 21 , Figs. 36 - 49 .) 
(I have studied those nerve cells which occur in the cerebral, 
pleural, and pedal ganglia. Three kinds of these cells may be 
readily distinguished and described in succession : (1) colossal 
cells, which are found only in the cerebral ganglion; (2) cells of 
medium size; and (3) small cells.) 
Colossal ganglion cells ( Figs. 43-49).—The number of the nu¬ 
cleoli in the nuclei of these cells varies from about six to thirteen; 
they are also variable in regard to the position which they 
occupy in the nucleus, and though always excentrically placed 
they never lie in contact with the nuclear membrane. Some¬ 
times all the nucleoli in a given nucleus are of approximately 
equal size, but as frequently one or two are several times larger 
than any of the others. Where such larger nucleoli occur along 
with a number of smaller ones, the former are usually vacuolar 
in structure ; sometimes nearly all the nucleoli contain vacuoles, 
in other cases none of them are vacuolar. Quite often the 
nucleoli in a nucleus show slight differences in their staining 
intensity, and one of them may stain quite differently from the 
rest (Figs. 44 and 46). None of the nucleoli have limiting 
membranes. No cases of nucleolar division were found, unless 
those cases where two nucleoli lie near to one another may 
represent the completion of such a division. 
Ganglion cells of medium size (Figs. 37-42). —In these the nu¬ 
cleoli vary in number from one to four, two or three being the rule. 
Those of the same nucleus frequently show differences in size 
and form, as well as slight staining differences. In only one 
1 For the observations of other writers on germinal spots in Hirudinea , cf. 
O. Hertwig (’76), Leydig (’49), Whitman (’78), and Platner (’89c). 
