CHAPTER 14 



GROWTH IN TERMS OF WATER AND SOLIDS 



1. Percentage of water in blood. 2. Percentage of water in brain and spinal 

 cord. 



(1) Percentage of water in the blood. Hatai (MS '15) has de- 

 termined the percentage of water in the blood of a small series 

 of Norways. 



The Norways were recently caught and examined before the 

 day's feeding. The rat was chloroformed, but before the heart 

 ceased beating it was exposed in situ, the tip clipped away and 

 the blood from it caught in a small glass weighing bottle. The 

 fresh weight was immediately taken and after drying at 95C. 

 for a week the weight of the residue was obtained. The results 

 are given in table 87. 



TABLE 87 

 Giving the percentage of water in the blood of the Norway rat, Hatai (MS., '15) 



(2) Percentage of water in the brain and spinal cord. Since the 

 percentage of water in the nervous system is most closely linked 

 with age, a precise determination in the case of the Norway rat 

 is wanting, by reason of the difficulty of rearing the Norway in 

 captivity. A few data are however at hand. 



From Norways born in captivity from trapped females we 

 obtain the percentages according to age, given in table 88. It 



211 



