308 



GROWTH IN WATER AND SOLIDS 



On the percentage value of the loss in weight on passing from 

 the room dried to the oven dried condition. In general the loss 

 of water in passing from the room-dried to the oven-dried 

 state is about 8.3 per cent of the room-dried value, and the oven- 

 dried weight is therefore 91.7 per cent of the room-dried. Table 

 164 gives the several values, according to the part of the skeleton, 

 as determined for the four body-weight groups which have been 

 selected. 



3. Percentage of water in the brain and spinal cord. Using 

 stock rats from the colony at The Institute, the percentage of 



TABLE 164 



The percentage in weight lost by room-dried bones after oven drying at 96C. Based 

 on the averages of the percentages as determined for each of the forty-two groups 



water has been determined for the brain and spinal cord by 

 Donaldson ('16). The values obtained by this study replace 

 those previously published (Donaldson '10). The methods of 

 removal are given on page 206. The rats were reared on a scrap 

 diet. The fresh brain or cord was weighed in a closed bottle, 

 then dried at 90-95C. until the dried weight was constant 

 and the difference taken as the amount of water. 



By the use of formulas (47)-(49a) for the brain and formulas 

 (50)-(52d) for the spinal cord, the values for table 157 after 10 

 days of age, were obtained and also those for the respective 



