IO6 LEO LOEB. 



the experiment. All the guinea pigs weighed between 400 and 

 500 grams. These animals were therefore less affected in their 

 general health by the lack of sufficient food than the animals in 

 the other series. Only guinea pig No. IV. showed marked 

 weakness. The duration of the experiment was on the average 

 somewhat shorter than in series III. and IV., and it is possible 

 that this factor also has something to do with the result. But it 

 is probable that the greater weight of the animals in the beginning 

 of the experiment is mainly responsible for the lack of the 

 development of hypotypical ovaries. 



First Series of Experiments (See Table IV.). In this experi- 

 ment the quantity of food given and changes in weight of the 

 animals had not been determined with the same accuracy as 

 in the later series. While we must consider the possibility of 

 errors in the figures for the weight of the animals it is probabla 

 that the error on the whole is not considerable. In most cases 

 the amount of food was increased for several days during the 

 experiment and there was therefore a transitory gain in weight 

 during a certain period. Animals a, b, c and d had been 

 thyroidectomized some time previous to the beginning of the 

 experiment; the remaining five animals had been normal. 



Guinea Pig No. a. Ovaries: Atretic yellow bodies (remnants 

 of old corpora lutea). Hypotypical ovaries of second order. 

 Hypotypical uterus. Mammary gland: Much gland tissue. 

 Resting, intermediate gland. 



Guinea Pig No. b. March 20, weight 650 grams; April 7, 600 

 grams; April 30, 280 grams. Ovaries: Retrogressing corpora 

 lutea, good follicles of all sizes. Large follicles with granulosa 

 degeneration; follicles in various stages of connective tissue 

 atresia. Not hypotypical ovaries; but no mature follicles de- 

 veloped and ovulation was delayed. Uterus: With ordinary 

 surface epithelium and glands. Some vacuoles in surface epi- 

 thelium. Fibrillar mucosa. Some cystic gland ducts at surface. 



Guinea Pig No. c. March 20, 350 grams; April 7, 275 grams: 

 April u, 175 grams. Found dead. Ovaries: With atretic 

 yellow bodies. Hypotypical ovaries of first order. Hypotypical 

 uterus. 



Guinea Pig No. d. Weight March 20, 500 grams. Receives 



