302 SHINKISHI HATAI 



in the cord of the castrates which amounted to 5.3 per cent (an 

 average of all groups — Donaldson and Hatai '11). For the lack 

 of agreement in this character between the two series no adequate 

 explanation can yet be given. 



PERCENTAGE OF WATER IN THE BRAIN AND IN THE SPINAL CORD 



Previous work (Donaldson and Hatai '11) has shown that 

 castration does not modify the percentage of water either in the 

 brain or in the spinal cord. The present series supports this 

 conclusion as will be seen from table 1. 



The difference between the castrated and control rats gives 

 0.07 per cent in the case of the brain and 0.17 per cent in the cord, 

 both in favor of the control. The difference is however too small 

 to be significant and thus justifies our previous statement. 



WEIGHT OF HYPOPHYSIS 



The hypophysis shows a most striking difference in weight 

 between the castrated and control rats. The diiference amounts 

 to nearly 74 per cent in favor of the castrated rats. The differ- 

 ence is shown not only in the final average but also in all four 

 groups and in each litter. This enlargement of the hypophysis 

 following castration is certainly the clearest alteration so far 

 found. 



So far as I know there is only one investigator who used the 

 albino rat for studying the effect of castration on the weight of 

 the hypophysis. This is Barnabo ('08) who gives three series of 

 experiments which were conducted in the following manner: 



Series 1. Bilateral section of vas deferens. This series comprises 

 three rats. 



Series 2. Section of vas deferens on one side and castration on 

 the other. This series comprises two rats. 



Series 3. Bilateral castration. This series comprises three rats. 



The operation was performed on sexually mature rats (112 

 grams in average body weight) and the period between operation 

 and death was on the average seventy-six days. The average 

 weight of the hypophysis was 0.015 grams corresponding to the 



