GONADOTROPIC SUBSTANCES 



and luteinization or more simply and perhaps less adequately 

 on the total weight-change in the paired ovaries. In the case 

 of prolan in which the weight-change is much less closely re- 

 lated to dose than is the case if anterior pituitary extract is 

 used, a better criterion would be the frequency of significant- 

 ly increased ovarian weight in a group of animals. There are 

 available no adequate data on the relationship between 

 weight-change or frequency of weight-change of ovaries and 



0.25 0.5 t.O 1.5 



Mgm. standard powder 



Fig. 40. — The appearance of oestrus and or corpora lutea in immature rats re- 

 ceiving different doses of one preparation of prolan. Ten animals were used for 

 each dose. From Coester, Arch. exp. Path. Pharm., CLXVIII (1932), 745-52. 



dose. On the other hand, Coester (193^) has determined the 

 frequency of oestrus and luteinization produced by several 

 preparations of prolan given to groups often rats. The curves 

 he obtained with one preparation are reproduced in Figure 

 40. Two facts emerge from his studies: (i) oestrus may be 

 produced by a fraction of the dose required to produce 

 luteinization, and (2) different preparations of prolan vary 

 in the relationship between oestrus-producing and luteinizing 

 doses. From the latter fact it may be argued that there exist 



[219] 



