104 INTERNAL SECRETIONS OF THE OVARY 



Simond, therefore, correct to a standard animal weight of 140 

 gms. by the formula: 



P 



where U is the corrected weight or volume of the unit, d the un- 

 corrected weight or volume, and P the weight of the animal in 

 grams. The number of rat units per c.c. or gm. of a preparation 



P 



is thus —J • 



a X 140 



Marrian and Parkes (438), however, failed to find that a cor- 

 rection of this nature was necessary. 



Table 5. — Influence of weight of Rat on 

 Unit of (Estrin 



(Adapted from Bugbee and Simond). 



Weight of the unit. Little work appears to have been done 

 on the comparative amounts of oestrin required to produce 

 oestrous symptoms in different species, but from the weight 

 effects discussed in the previous section it would seem that 

 very considerable variation must occur. Allen and Doisy (21) 

 state that two to four times the amount is required for the rat 

 as compared with the mouse, but Coward and Burn (146) 

 found that the doses required were identical for these two animals. 

 Bugbee and Simond (no) confirm Allen and Doisy in finding 

 that the rat unit is two to eight times as great as the mouse unit. 

 As regards larger animals no information appears to be available, 

 but it seems doubtful whether a weight for weight ratio will be 



