1 6 FEMALE BITTERLING I 



the number of = O-groups. When one = O is replaced by 

 one -OH-gtoup, the activity is weakened ij times. When 

 the second = O is replaced by an -OH, there is again a weak- 

 ening of from ^ to 10 times. 



The duration of activity, in the case of the allo-pregnanes 

 and the pregnanes, also depends on the number of = O or 

 -OH-groups. When one -OH is replaced by an = O, the 

 duration of the activity is shortened about i ^ times. When 

 a second -OH is replaced by an = O, the duration of the 

 activity is shortened again i ^ times. 



It is relevant at this point to deal with the reactions of 

 some of the corticosteronc-derivatives. 



a, Corttcosterone. With concentrations of 200, 400, 600 

 and 750 7 per 750 ml water, the following growth-curves 

 were obtained (Fig. 17). The characteristics of these curves 

 are:— 



Latend period, i hour. Linear growth ends after 4^ 

 hours. After this the growth-curve remains normal. 



Corticosterone 



Fig. I 7. Ovipositor growth curves after administration of corticosterone. 



b. Desoxycorticosterone. With concentrations of 25^, 4, 

 5, 7 3^, 10, 15, 20 and 60 y per 750 ml water the following 

 growth-curves were obtained (Fig. 18). The characteristics 

 of these curves are:— 



