148 



CM. JACKSON 



body- weight) to 0.0048 gram (0.021 per cent of the body- weight). 

 This would indicate a decrease of about 27 per cent in absolute 

 weight. The ovary, however, is an organ which (like the thyroid 

 gland) is quite variable and somewhat difficult to dissect out with 

 accuracy, so a much larger number of observations would be 

 required for a final conclusion. 



HYPOPHYSIS 



In the hypophysis (table 24) there is normally a sexual differ- 

 ence in weight, observable in rats above 50 grams in body-weight 

 (Hatai '13). As in the case of the suprarenal glands, the hypo- 

 physis normally becomes relatively heavier in the female. 



In the rats held at constant body-weight from the age of three 

 weeks to six weeks, there is what appears to be a sexual differ- 

 ence, the one male with a hypophysis of 0.0016 gram (0.0068 

 per cent of the body-weight), while the two female hypophyses 

 each weigh 0.0018 gram (0.0079 per cent of the body-weight). 

 These are probably mere accidental variations, however, as in 

 the three to ten weeks series the difference in the relative weight 

 is insignificant (0.0084 per cent of the body-weight in the males, 

 and 0.0086 per cent in the females). In any event, however, 



TABLE 24 



The hypophysis; average absolute weight, average percentage of net body-weight and 



range indicated 



DESCRIPTION OF RATS 



absolute weight 

 (and range): grams 



relative weight 



(and range) 



PER CENT 



Normal at 3 weeks' CHatai '13) 



Controls at 3 weeks* 



Body-weight constant 3 weeks (age of 3 to 6 weeks) 

 Body-weight constant 7 weeks (age of 3 to 10 weeks) 



Normal at 10 weeks (Hatai '13) 



Controls at 10 weeks 



0.00175 



0.00178(0.0012-0.0022) 



0.0016 



0.0018 



0.0021 (0.0016-0.0024) 



0.0020(0.0010-0.0033) 



0.0054 



0.0084 



0.0062 (0.0059-0.0067) 



0.0054 (0.0046-0.0067) 



0.0070 



0.0070(0.0052-0.0084) 



0.0068 



0.0079 (0.0076-0.0082) 



0.0084 (0.0057-0.0110) 



0.0086(0.0043-0.0135) 



0.0042 



0.0065 



0.0040 (0.0038-0.0042) 



0,0048 (0.0040-0.0062) 



* No sexual difference apparent. 

 t Gross body-weight. 



