ANIMAL PRODUCTION. 369 



sire as to produce nu appreciable decrease I)otli iu size and vitality of offspring. 

 In experiments with chicks the results, as indicated by the infertility of eggs 

 ajid the death of embiyos or young chicks soon after hatching, showed that the 

 influence of lead poisoning in the case of the male distinctly affected the 

 vitality of the offspring. 



Physiology of reproduction (Wisconsin Sta. Bui. 250 (1915), p. 46). — In 

 trials with guinea pigs by L. J. Cole and H. Ibsen it has been shown that the 

 size of offspring is controlled to some extent by the length of the gestation 

 period, the young being smaller with a short period. The size of the mother, 

 Bind and amount of her food, and her ability to utilize it for the development 

 of the fetuses are even more important in determining the size of offspring. 

 Small and young mothers tend to produce small offspring, especially when the 

 litter is large. With small litters the weight of the mother increases up to 

 parturition. With large litters, however, her weight remains stationary or even 

 drops during the last days of pregnancy, evidently due to the fact that all the 

 nutrients in the food are required for merely maintaining the weight of the 

 mother and fetuses. Numerous weighings have disproved the assumption that 

 female young gain steadily from the day of birth while males lose in weight. 

 There is no correlation with sex in this respect, both sexes tending to lose in 

 weight during the first few days. Neither is there any constant relation between 

 the size of individuals and the order of their birth in the litter. 



Sex studies. — VII, On the assumption of male secondary characters by a 

 cow with cystic degeneration of the ovaries, R. Pearl and F. M. Surface 

 (Jlainc Sia. Bui. 237 (1915), pp. 65-80, pis. 3). — This paiier describes the repro- 

 ductive history of a cow, which presents the following points of interest. 



" The cow was initially a i)erfect female, bearing calves and making a very 

 high milk record. Later she failed to come in heat, and gradually, but in the 

 end to a very marked degree, took on male secondary sex characteristics, both 

 in behavior and structure. The gonads of this animal, examined subsequent to 

 the change in secondary characters, were exactly like those of a normal cow, 

 save in the one respect that the follicles were not breaking and discharging ova, 

 but were forming follicular cysts, or becoming atretic, and because of this no 

 corpora lutea were formed. The interstitial secreting mechanism of these 

 ovaries was absolutely normal, both in respect of number of cells and the 

 cytological characteristics of the individual cells. 



"The evidence from this case strongly suggests that one function of the 

 corpus luteum, through its internal secretion, is to maintain in full development 

 the female secondary sex characters. Repeated injections of a suspension of the 

 dessicated substance of the anterior lobe of the pituitary body failed to bring 

 about any change in the sex behavior of this cow after it had assumed a male 

 character." 



Sex ratios in pigeons, together with observations on the laying, incuba- 

 tion, and hatching of the eggs, L. J. Cole and W. F. Kirkpatrick (Rhode 

 Island Sta. Bui. 162 (1915), pp. 463-512, figs. 5).— A continuation of the work 

 noted above. 



It was found that " the normal ratio of the sexes of pigeons hatched is 105 

 males to 100 females. The death rate of squabs is especially high for the first 

 two or three days after hatching, and at about 10 to 15 days of age. When the 

 two squabs are of distinctly different size before the banding age (10 to 15 days), 

 the larger squab is more often a male than a female. The death rate for the 

 two sexes, in bisexual broods, is essentially equal. There is no marked tend- 

 ency for one sex to be weaker than the other in bisexual broods, and there is 



