244 



Scientific Proceedings (129) 



117 (2077) 



Resistance of pigeons to the lethal action of iletin (insulin) with 

 observed effects on reproduction. 



By OSCAR RIDDLE. 



[From the Carnegie Station for Experimental Evolution, Cold 

 Spring Harbor, N. Y.] 



The pancreatic extract used by us is prepared under the name 

 iletin (insulin, Lilly) ; it was supplied by the makers and bore 

 the date of preparation. It is prepared by the method of Bant- 

 ing 1 and Macleod 2 , one unit of the extract being the amount 

 necessary to reduce the blood sugar of a kilogram rabbit to 

 0.045 per cent. At this percentage the rabbit often goes into 

 convulsions and death sometimes follows. This unit of iletin 

 or insulin may therefore he considered the lethal dose for a 

 kilogram rabbit. 



We are using the pancreatic hormone as a part of a more 

 general study on the relation of the various incretions to re- 

 production and to sex. Our specific purpose here was to learn 

 whether as a consequence of the hypoglycemia induced by this 

 extract all ovulations would be suppressed in the pigeon by a 

 dosage which should leave the other conditions necessary for 

 reproduction essentially undisturbed. I have earlier reported 3 

 a marked hypertrophy of the suprarenals at the ovulation pe- 

 riod, and in collaboration with Honeywell 4 have shown that 

 parallel with this hypertrophy there regularly occurs in pigeons 

 a marked increase of blood sugar coincident with ovulation. 

 Other unpublished work by Honeywell and myself has made it 

 clear that in each of two very common causes of suppressed 

 ovulation the blood sugar is abnormally low. Such earlier 

 observations have led to the view that a low blood sugar tends 

 to suppress ovulation in birds. This conception is again sup- 

 ported by the results of the present study. It is found that 



i Banting and Best, Jour. Lab. and Clin. Med., 1922, vii, 404. 

 * Banting, Best, Colli]), Macleod and Noble, Amer. Jour. Phi/siol., L922, lxii, 

 162. 



8 Riddle, PBOO. Soc. Exp. Biol, and Med., 1922, xix, 122. 



4 Honeywell and Riddle, PBOO. Soc. Exp. Biol, and Med., 1922, xix, 280. 



