268 NAOKI SUGITA 
VIII. SIZE AND GROWTH CHANGES IN SOME NERVE CELLS IN THE 
MAMMALIAN BRAIN 
Albino rat. The results obtained by me regarding the size 
and the growth changes of the pyramidal cells and of the ganglion 
cells in the cerebral cortex of the albino rat were summarized in 
a previous study (Sugita, 718 c¢). Four of the conclusions are 
here quoted: 
1. The full size of the pyramids in the lamina pyramidalis is 
cell body 21 x 27 uw and nucleus 18 x 20 uw in the fresh condition 
(on the slide, respectively, 16x 21 yu and 14x15uy). The full 
size of the ganglion cells in the lamina ganglionaris is cell body 
27 x 37 w and nucleus 23 x 25 uw in the fresh condition (on the 
slide, respectively, 21 x 29 u and 18x 19 yn). 
2. The cell body and the nucleus of the pyramids attain their 
maximum size at twenty to thirty days in age. Up to ten days 
they still retain their fetal morphology. After having passed 
the maximum size at about twenty-five days, they diminish 
somewhat in size, but the internal structure differentiates as the 
age advances. 
3. The cell body and the nucleus of the ganglion cells attain 
nearly their maximum size at ten days, when they remain still 
in fetal form. After this stage, the size of the cell body still in- 
creases slowly but steadily as the age advances, while the nucleus 
remains nearly unchanged in size throughout life. 
4. Taking a general view of the data already presented in this 
series of studies, it is very interesting to observe that the thick- 
ness of the cortex, the total number of the cortical nerve cells, 
and the size of the cortical cells, all attain nearly their full values 
at the same age of twenty days; that is, at the weaning time of 
the albino rat. 
For comparison with these results on the cells of the cerebral 
cortex, there are some observations by Addison (711) on the post- 
natal growth of the Purkinje cells in the cerebellar cortex of the 
albino rat. His material was also obtained from the rat colony 
at The Wistar Institute and the cerebellum was fixed in Ohl- 
macher’s solution, imbedded in paraffine, and stained with 
