64 



ANATOMY 



in table 26 the erythrocytes of the female are less resistant than 

 those of the male, a result which suggests that the serum of the 

 female may contain less water than that of the male of like age. 

 Refractive index of the blood serum at different ages. The 

 observations were made with a Pulfrich refractometer on serum 

 obtained by centrifuging blood obtained directly from the heart. 

 From 35 age groups the values are given in table 27 and in 

 chart 5 (Hatai, '18 b). 



1.350 

 1,349 

 1.3A8 

 1,341 

 1.346 

 1.345 

 1.344 

 1.343 

 1.342 

 1341 



50 K» 150 200 250 300 350 400 450 500 550 



Chart 5 Showing the refractive index of blood serum at different ages. 



Chart 5 shows the manner in which these values change on 

 age. The index is slightly higher before suckling than im- 

 mediately after. Three periods are recognized (1) The suck- 

 ling period — to 21 days (2) From end of suckHng period to 

 puberty, at about 80 days, and (3) From puberty to the end 

 of the record. 



The percentage of water in the serum on age falls in such a 

 manner as to give a graph which is the inverse for the increase 

 in the refractive index — see chart 4. 



