128 HENRY H. DONALDSON 



When young rats were underfed for three weeks and then 

 returned to a normal diet, Hatai found that their subsequent 

 increase in body weight was somewhat more rapid than that of 

 the control group, and in the case of the males, the final weight 

 even greater. Hatai's table IV ('07) is here repeated. 



TABLE 4. 



ENCEPHAI.ON SPINAL CORD 

 PER CENT PER CEN1 



Male controls 77.50 69.71 



Male experimented 77 . 75 70 . 05 



Female controls 77.50 69.40 



Female experimented 77 . 75 70 . 10 



Taking both sexes together, the experimented groups, as shown 

 in the above table 4, had on the average a percentage of water 

 in the brain greater by 0.25 per cent and in the cord by 0.52 per 

 cent. As will be observed, this treatment produced a rather 

 greater alteration in the percentage of water than was obtained 

 by Watson in the case of the mated and unmated females. 



In the foregoing instance there were fourteen pairs of brains 

 between which comparisons were made, and in thirteen of these 

 the experimented rats show a greater percentage of water. In 

 the case of the spinal cord, eleven pairs out of a total of fourteen 

 show the experimented rats to have the greater percentage of 

 water, so that here again although the variation induced by the 

 treatment is not great, yet a slight change seems to be really 

 effected. 



In another series of observations Hatai ('08) got still more 

 marked differences in the percentage of water. In this case there 

 were seven pairs of contrasted individuals. Seven individuals 

 were used as controls and seven others, from the same litter, fed 

 with small quantities of a varied diet and thus stunted. When 

 these latter had attained an average age of about 140 days, they 

 were put on a full normal diet for thirty days and then both lots 

 were killed and examined at the same time. 



During the thirty days of normal feeding, the stunted rats 

 grew in weight and length. When killed at this time it was found 

 that the stunted rats had in both brain and cord a distinctly 



