Donaldson and Schoemaker, Absorption of Water. 197 



TABLE X. 



Control Frog. Absorbing Frog. 



Average Body Weight in grams 37-9 35 7 



Percentage increase in the f observed i6.8<i 



Weight of tne Absorbing \ calculated from ^ o /y 



Frog, after i8 hours ( dried residue ) ' '" 



Percentage of Water in the 



Spinal Cord 79-9% 84.7% 



Absolute Weight of dried Kesiilue 



of Cord in grams 0.0093 0.0084 



Looking- at the tables, we observe first that the percentage 

 of water in the absorbing cord increases as the length of the 

 time increases. The percentage of water also increases more 

 rapidly than the increase in the weight of the absorbing cord, 

 as there is a correlated loss in the amount of dried substance. 



On estimating the moist weight of both the control and 

 absorbing cords on the basis of the percentage value of the 

 weight of dried substance, we find as given in the three tables 

 under "percentage increase in the weight of the absorbing 

 cord — calculated from dried residue," that the percentage of 

 gain is approximately equal to the observed percentage. The- 

 oretically, it should be exactly equal to the observed percent- 

 age, but slight inaccuracies in weighing to tenths of a milli- 

 gram, which are here relatively important, will explain the 

 discrepancies. 



It seems plain, therefore, that the gain in weight of the 

 absorbing cord is due to the imbibition of water, and that in 

 this process solids diffuse out of the cord. Casual observations 

 on the spinal cord of the white rat do not reveal any tendency 

 on the part of the cord of that animal to take up water in the 

 way the cord of the frog does. For this reason we should 

 hardly expect this reaction to be found in other mammals. 



Summary. 



From these results we conclude that the gain in the 

 weight of the absorbing cord is due to the imbibition of water, 

 and that the cord, when taking up water, also loses in solids. 

 In this process there is wide individual variation. 



In addition to the general effect of season as expressed in 



