76 



ANATOMY 



6. Nervous system, (a) Central. (1) Brain. 



Specific gravity 1.050-1.056, (Reichardt '06). 



For brain weight see chapter 7, p. 206, and table 144. 



For percentage of water see chapter 8, p. 308, and table 157. 



For chemical composition see chapter 9, p. 320, and table 178. 



TABLE 42 

 Showing the number of pairs and location of the two types of lymph nodes 



TABLE 43 



The number of mitoses in 18 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. Hamilton ('01). 



STAGE OF DEVELOPMENT 



For vascularity see chapter 3, page 56. 



Cell division. Cell division in the central nervous system 

 continues after birth but soon ceases, save in the cerebellum. 



The observations of Hamilton ('01) are given in table 43. 



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

 results given in table 44. 



