1919] 



ANIMAL PRODUCTION. 173 



the testicle, the ovary, the corpus luteum, the uterus, the mammary gland, and 

 the placenta receive more summary treatment. The illustrations are mainly 

 tracings showing the intluence of extracts on muscular action and drawings 

 of histological preparations. 



The placenta regarded as a gland of internal secretion, II. T. Frank {Surg., 

 aynecol., and Obstct., 25 {1911), No. 3, pp. 329-331).— \ review of the literature 

 is given and a statement made of experimental results secured by the author. 



Injection of placental extract caused great increase in functional activity 

 of the mammary gland and the uterus of rabbits. The extract was found 

 to have chemical characters and physiological effects closely resembling those 

 of corpus luteum extract. It is suggested that the placenta does not secrete 

 a hormone of its own but merely acts as a storehouse for corpus luteum 

 secretion, especially during the latter part of pregnancy. 



Histological study of ovaries engrafted on castrated male guinea pigs 

 and removed at the onset of lactation, :M. Athias {Compt. Rend. Soc. Biol. 

 [Paris], 79 {1916), No. 12, pp. 553-556). — The author has examined histologi- 

 cally 8 guinea pig ovaries that had been grafted under the skin of young 

 castrated males of the same species. After an interval of time the mammary 

 gland of the male became functional. The four gi-afts removed during the 

 first three days of lactation are reported on here. Interstitial gland tissue and 

 numerous mature and atretic follicles were found, but no true corpora lutea. 



On the causes responsible for the developmental progress of the mamniary 

 glands in the rabbit during the latter part of pregnancy, J. Hammond {Proc. 

 Roy. Soc. \_London], Ser. B, 89 {1911), No. B 622, pp. 534-5^6, pi. 1).—As a re- 

 sult largely of the work of Ancel and Bouin (E. S. R., 21, p. 669), the author 

 regards it as established that the corpus luteum provides the stimulus for the 

 growth of the mammary gland during the early stages of pregnancy. His ob- 

 ject in the present paper is to report investigations dealing with the develop- 

 ment of the mamniary gland during the glandular phase, which in rabbits 

 begins about the sixteenth day of pregnancy. 



Contrary to accepted belief the corpus luteum of pregnant rabbits was found 

 not to become atrophied during the latter part of gestation, but to maintain 

 its size even into the period of lactation. In a series of " pseudo-pregnant " 

 rabbits, i. e., females made to ovulate by coitus with vasectoraized males, the 

 corpora lutea and mammary glands developed as in pregnant individuals until 

 the sixteenth day after coitus and then decreased in size. By operative muti- 

 lations of the uterus of certain pseudo-pregnant does, the author caused the 

 development of masses of decidual cells identical in appearance with the ma- 

 ternal placenta. In such animals the corpora lutea and the mammary gland 

 followed the same course as in ordinary pseudo-pregnant individuals. Preg- 

 nant females, from which the fetuses but not the maternal placentae were re- 

 moved by operation on the thirteenth to fifteenth days of gestation, also showed 

 atrophy of corpora lutea and mammary glands. It is held that the presence 

 of embryos is necessary for continued existence of corpora lutea, and that the 

 presence of the latter stimulates the mammary gland to complete development. 



The cyclic changes in the mammary gland under normal and pathological 

 conditions, L. Loeb and C. Hasselberg {Jour. Expt. Med., 25 {1911), No. 2, pp. 

 285-321). — Two studies are presented based upon the histological examination 

 of the mammary gland in normal guinea pigs and those that had been sub- 

 jected to various operations. 



I. The changes in. the nonpregnant guinea pig (pp. 285-304). — A definite 15 

 to 19 day cycle was found in the activity of the mammary gland of the non- 



