42 



ANATOMY 



TABLE 22 



The number of mitoses in 13 consecutive sections, each section 6.75 n in thickness, 

 from the brain and spinal cord of rats at different stages of development. The 

 fetus weighed 0.78 gms. and had a crown-rump length of 17 mm. It was probably 

 at 17.5 days of gestation. 



For the first 25 days after birth Allen ('12) has obtained the 

 results given in table 23. 



TABLE 23 



Showing the number of mitoses per cubic millimeter of nerve tissue in the central 

 nervous system of the stock Albino at certain levels. The figures are taken from 

 calculations of the volume of tissue and based on the number of mitoses in the con- 

 secutive sections at each level of the cord, five in the largest portion of the cere- 

 bellum and five in the cerebrum in the region of the optic chiasma. The letters 

 (a) (b) and (c) refer to different rats of the same age 



