306 SHINKISHI HATAI 



Percentage of water in the brain and spinal cord. The difference 

 between the spayed and controls with respect to water content 

 is negHgible, and thus it is concluded that spaying does not 

 modify the water content of these structures. 



Weight of hypophysis. The weight of the hypophysis in the 

 spayed is slightly greater than that of the controls; the difference 

 amounts to 3.84 per cent. This amount of difference however 

 will easily fall within the experimental error on account of the 

 minuteness of the gland as a whole. 



Furthermore, when this difference, 3.84 per cent or 0.0004 grams 

 in absolute weights compared with the difference shown by the 

 castrated rats (73.62 per cent) we feel still safer in concluding that 

 the difference is most likely due to slight experimental errors or 

 incidental variation and that consequently spaying does not 

 modify the weight of the hypophysis. 



The present results on the spayed rats are contrary so far as 

 the hypophysis is concerned, to the results obtained, for instance, 

 by Fichera ('05) in guinea pigs and rabbits, and Kon ('08) in 

 women. These investigators noticed a striking enlargement of 

 the hypophysis as the result of spaying. On the other hand 

 Marrassini and Luciani ('11) find no hypertrophy following spay- 

 ing in guinea pigs and rabbits. Thus we see that discordant 

 results are again presented by these authors. The observations 

 of Marrassini and Luciani appear to have been the more carefully 

 made. 



In this connection the following general comment on the subject 

 of the removal of sex glands may be made. 



The question of the enlargement of the hypophysis following 

 the removal of either of the sex glands is difficult to solve, not 

 because the operation is complicated, but because the hypophysis 

 is such a minute organ and its normal variability is great. 



This difficulty is further increased by the fact that its varia- 

 tion m weight tends to be greater when different litters, or still 

 more, when different strains of the same race, are compared. 

 These difficulties however may be reduced to a minimum by 

 taking both the control and the operated animals from the same 



