IIO LEO LOEB. 



jected to insufficient feeding extending over periods varying 

 between 33 and 6 days. In the majority of experiments the 

 loss in weight varied between 25 per cent, and 35 per cent, of 

 the initial weight. In some cases the loss was greater, in others 

 less. In the controls there was usually a gain in weight during 

 the experiment, but in two cases there was some loss and in one 

 the loss was as much as 20 per cent, of the initial weight. This 

 animal cannot be considered as a perfect control. In the controls 

 the sexual cycle took its normal course and ovaries and uterus 

 were normal in seven animals. In three of these pregnancy 

 was present which proceeded normally. In several others ovula- 

 tion occurred during the time of the experiment and the follicles 

 developed in a healthy manner. In the one case, in which the 

 animal lost 20 per cent, of its weight, the ovaries were not yet 

 hypotypical, but some change was noticeable tending in that 

 direction. Of the animals subjected to lack of a sufficient 

 quantity of food the ovaries were hypotypical in eighteen cases. 

 There were differences in the degree in which this condition had 

 developed; while the ovaries of some showed a hypotypical 

 condition of the first order, in others hypotypical ovaries of the 

 second order were present. In the former the development of 

 the follicles proceeded only to that stage in which the follicles 

 were of small-medium size. At this stage atresia set in, while 

 in the second kind a few follicles developed to medium or almost 

 medium size; while others became already atretic at an earlier 

 stage. In no case were large follicles produced in any of these 

 ovaries. In three other cases changes were noticeable in the 

 ovaries which suggested a beginning in the direction toward the 

 development of hypotypical ovaries, while in five animals hypo- 

 typical changes were not yet noticeable, but an inhibition of 

 ovulation had occurred owing to the fact that the large follicles 

 failed to mature. We see then that in all the animals a failure 

 of the follicles to mature occurred and in 69 per cent, of the 

 animals the ovaries were hypotypical. In addition pregnancy 

 was found in none of the animals. In one of them abortion 

 had occurred, with certainty and in a second one with great 

 probability, in both cases probably as a result of the underfeeding. 

 If we now inquire into the causes of the variability in the 



