294 CARL RICHARD MOORE. 



grams to more than two kilos, yet averages were taken on the 

 group as a whole. In his Fig. 7 (curves 13 and 14), however, in 

 which normal males controlled operated males and normal females 

 the operated females from the same litter (ages not given), the 

 indications are that the castrated males increase in weight, com- 

 pared with the normal males, for a period of four months after 

 operation. One is unable to judge, however, the comparative 

 ages of all concerned and undoubtedly this would make a consider- 

 able difference in the results. This writer, as well as Hatai, be- 

 lieves that after castration there may or may not be a hypertrophy 

 of the hypophysis, depending upon unknown factors; if hyper- 

 trophy does not take place, the animal undergoes a relative in- 

 crease in weight, whereas there is an absence of a relative body 

 weight increase if the hypophysis does not so react. If this is 

 later proven to be correct, one will be unable to properly interpret 

 weight differences following sex-gland removal without consider- 

 ing the possibilities of secondary influences dependent upon the 

 hypophysis. One is led to believe from the experiments of 

 Livingston with the rabbit that totally spayed females are hindered 

 in growth ; his curves show the normal female weight to be above 

 that of the spayed females. 



Thus Stotsenburg and Hatai are in practical agreement that the 

 testis does not influence the growth of the rat, whereas in the 

 rabbit Livingston believes that the testis retards growth ; castrated 

 animals are heavier than controls. My own experiments show 

 but little effect in the guinea pig from castration, though there is 

 a slight indication that the testis stimulates growth. As to the 

 effects of the ovary on growth, Stotsenburg and Hatai agree that 

 elimination of the rat ovary results in relative increases in the 

 growth curves ; Livingston, however, believes that ovariotomy 

 lowers the growth curves in the rabbit. In the guinea pig my 

 experiments show a slightly reduced growth curve for the spayed 

 females up to the end of the first year. 



IV. BODY LENGTH OF NORMAL AND OPERATED ANIMALS. 



The total body length of each animal was determined as each 

 was killed on the 36oth day, and it appeared desirable to record 

 these observations for the bearing they may have on growth in 



