98 



GROWTH OF PARTS AND ORGANS 



moved before weighing. The data are from observations by 

 Jackson ('13), as well as from those made at The Wistar Institute. 

 A study of the data has not revealed any difference according to 

 sex and the graph therefore is for both sexes combined. The 

 graph in chart 18 and the values in table 71 have been determined 

 by formula (32). Hatai ('13); Jackson ('13). 



50 



150 



200 



250 



300 



350 



400 



450 



Chart 18 Showing the weight of thyroid gland of the albino rat according to 

 body weight. The observed weights are represented by 42 (Jackson) female 

 rats below 50 grams in body weight, and 49 (Wistar) male rats above 50 grams in 

 body weight; and 36 (Jackson) female rats below 50 grams in body weight, and 

 27 (Wistar) female rats above 50 grams in body weight. Table 71, formula (32) . 



Observed weight male. Calculated weight for both sexes, o Observed 



weight, female. 



The weight of the hypophysis on body weight. Technic: After 

 the removal of the brain, the hypophysis is readily picked 

 up from the floor of the skull with a small forceps. It is weighed 

 as removed. 



At about 40-50 days of age there appears a difference in the 

 weight of the hypophysis according to sex and with advancing 

 age this difference tends to increase. The female has the heavier 

 hypophysis. The graph for the male in chart 19 and the values 

 for the male in table 71 have been determined by formula (28). 



