108 SHINKISHI HATAI 



three distinct phases of growth. The first and last phases are 

 represented by the logarithmic curves, while the second is rep- 

 resented by a parabolic curve. Weight of ovaries : 



(Phase 1) = 0.010 log (Bd. wt. + 3) - 0.0082 



[Bd. wt. < 50] 

 (Phase 2) = 0.0425 - 0.00121 Bd. wt. + 0.0000108 Bd. wt.- 



[50 < Bd. wt. < 80] 

 (Phase 3) = 0.007 log (Bd. wt. - 105) + 0.0352 



[Bd. wt. > 110] 



The constants of the formulas were determined from 136 

 female rats and the relation between observed and calculated 

 values is shown in chart 8. The data used here were obtained 

 by Dr. Jackson from the rats kept at the University of Missouri. 

 These rats were all unmated excepting a few of the oldest (at age 

 of one year). It is therefore possible that the ovaries belonging 

 to the mated females may show some deviation from the values 

 given by the present formulas. 



9. Suprarenal glands. In this gland a sexual difference is clearly 

 shown. Consequently the growth of the suprarenals in weight 

 is treated separately according to sex and is represented by the 

 following formulas respectively. 

 Weight of suprarenals: 



Male = 0.0000855 (Bd. wt. + 3) +0.0113 log (Bd. wt. + 3) - 0.0093 

 Female = 0.00023 Bd. wt. + 0.00388 log Bd. wt. - 0.0020 



[Bd. wt. > 30] 



The constants of the formulas were determined from 145 males 

 and 113 females respectively. The relation between observed aild 

 calculated values is shown in chart 9. As is shown in the chart, 

 the sex difference becomes clearly marked in the rats of about 

 30 grams in body weight. This difference becomes greater as 

 the rats increase in weight. The calculated value of the female 

 glands is represented by the discontinuous line, and the ob- 

 served values, by circles. The male values are given by the 

 continuous line record and the black dots. The physiological 

 significance of the greater weight of the suprarenals of the female 

 has still to be investigated. 



