Hata, Centrosome in Nerve Cells. 35 
Von KO_ttiker is the first to report the centrosome in the 
mammalian central nervous system. He found the centrosome 
in a giant pyramidal cell of the posterior central gyrus of a man 
thirty years old. Later, Neris demonstrated the presence of 
the centrosome in the nerve cells of some adult higher mam- 
malia, but only under pathological conditions. He summarizes 
his observations as follows: ‘‘A l’état normal, un centrosome 
n'est pas visible dans les cellules nerveuses des mammiféres. Le 
processus pathologique rabique determine l’apparition du cen- 
trosome dans les cellules nerveuses des ganglions spinaux chez le 
chien et chez le lapin. Au cours de cette infection, le centro- 
some ne reste pas inerte; il semble se diviser; en deux; les deux 
centrosomes tendent a se separer et A emigrer dans deux direc- 
tions opposées. 
‘‘Les modifications nucléaires des cellules nerveuses au 
cours de l’infection rabique représentent pour nous des phé- 
nomeneés de régression, d’atrophie, précédés d’une tendance a la 
proliferations qui averte prematurément, tendance se traduisant 
uniquement par l’apparition du centrosome au sein du proto- 
plasme, sa division probable et le commencement de migration 
des deux centrosomes nouvellement formés.”’ 
He absolutely denied the presence of the centrosome in 
mammalian nerve cells in a normal condition as far as his obser- 
vations went. He further mentioned a possibility of the divis- 
ion of nerve cells in the mature animals, although he has not 
actually observed it. On the other hand, Miss Lewis’ obser- 
vations led her to doubt the dividing process in the adult nerve 
cells. But she does not base her statement upon the structure 
of the centrosome but on the fact that she has not noticed such 
cases of division although she has examined the preparations 
made from more than a dozen worms. The present writer also 
doubts the occurrence of division (mitotic) of matured normal 
cells in the normal condition for the following reasons: The 
sphere in an adult nerve cell is slightly different from that of 
young nerve cells. The centrosome in young cells shows a 
clear outline with a radial arrangement of the protoplasm, the 
radii originating from the central corpuscles or centrosome. The 
