EFFECT OF CASTRATION ON THE WHITE RAT 301 



TAIL LENGTH 



The tail of the castrated rats is sHghtly longer than that of the 

 controls; the difference is somewhat o^'er 5 per cent and occurs 

 in three out of the four groups (see table 1). 



Other experiments now in progress in our laboratory also indi- 

 cate the same relation. Consequently the difference found in the 

 present case should not be disregarded on account of its small 

 magnitude. The following conclusion is therefore made tenta- 

 tively: that the castrated rats, when compared with their controls 

 tend to have slightly longer tails. 



BRAIN WEIGHT 



The difference in brain between castrated and controls is 0.33 

 per cent in favor of the latter (table 1) . Although this difference is 

 so slight, nevertheless by reason of its persisitent occurrence it 

 cannot be neglected. It has been found previously (Donaldson 

 and Hatai '11) that castration in the albino rat reduces the weight 

 of the brain and the weight of the cord also somewhat below 

 those weights in the normal control rats. The deficiency in the 

 castrates amounted (as an average of all groups) to 3 per cent 

 in the brain and 5.3 per cent in the spinal cord. The deficiency 

 in the present experiment is far less, nevertheless its constancy in 

 direction, as well as the similar tendency among both the spayed 

 and the semi-spayed rats (see tables 2 and 3) force us to conclude, 

 though with considerable reserve, that castration tends to reduce 

 the relative weight of the central nervous system. The difference 

 in this deficiency among different strains suggests that the reduc- 

 tion may vary considerably according to the general condition of 

 the rats under experiment. 



WEIGHT OF SPINAL CORD 



Contrary to the case of the brain, the weight of the spinal cord 

 of the castrates is heavier than that of the control rats. The 

 difference amounts to 3.01 per cent. Thus the present series 

 gives in the cord results contrary not only to the brain but also 

 contrary to our previous findings in which we noted a deficiency 



