1919] ANIMAL PRODUCTION. 467 



those sexual organs of the freemartin which are present in the Indifferent sta 



develop toward the male condition, while anatomical developments that par- 

 ticularly characterize the later female stages, such as the proliferation of the 

 cords of Pfliiger and the union of the Mlillerian ducts to form the Uterus, do not 

 occur in the freemartin. The great variation found in the reproductive organs 

 of the freemartin is explained by the differences in the exact stage at which 

 the interstitial secretions of the male arc introduced into the circulation of the 

 female embryo and In the amounts thus introduced. 



The relations between the interstitial gland of the testicle, seminiferous 

 tubules, and the secondary sexual characters, L. Loeb iliinl. Jiul. Mar. Biol. 

 Lab. U'oof/s Hole, SJ t (1918), No. 1, pp. 33-.',S).— This paper discusses a case of 

 undescended testes in a guinea pig. 



Histological study of the testicles, which were found in the normal place of 

 the ovary, showed that spermatogonia were absent and that the seminiferous 

 tubules were lined with a single layer of epithelium, interpreted as cells of Ser- 

 toli, and surrounded by an unusual amount of interstitial tissue. Observations 

 on the living animal showed that sexual desire was normal. In spite of en- 

 largement of interstitial gland substance, male secondary sexual characters 

 were absent, there being, indeed, no penis. Microscopic examination of mam- 

 mary glands showed a typical female appearance. 



In an appendix the author compares this case with the findings of Liilie and 

 of Chapin in regard to freemartins, as noted above. 



The existence of a typical oestrous cycle in the guinea pig, with a study 

 of its histological and physiological changes, C. R. Stockakd and G. N. 

 Papanicolaou (Amer. Jour. Anat., 22 (1917), No. 2, pp. 225-288, figs. 30). — By 

 using a small nasal speculum to examine the vaginal canal of guinea pigs at 

 frequent intervals, it was found that the vagina of nonpregnant females is 

 filled with fluid for about 24 hours once every 16 days. The fluid is not abun- 

 dant enough to be detected on the vulva. It is a mucous secretion from the 

 uterus containing a large number of desquamated epithelial cells from the 

 vagina. After about 12 hours the latter become so numerous that the material 

 has a distinct cheese-like appearance. Leucocytes then invade the mass and it 

 is soon disposed of. 



Anatomical studies show that ovulation occurs during every one of these 

 periods, and that the actual rupture of the follicle occurs at the time the vaginal 

 accumulation^ is thick and cheese-like. The corpus luteum is held to control 

 these changes. 



A suggestion as to the process of ovulation and ovarian cyst formation, 

 S. S. Schochet (Anat. Rec., 10 (1916), No. 6, pp. 447-457).— The liquor derived 

 from mature ovarian follicles of the pig was found capable of digesting ovarian 

 tissue, muscle, ligament, and fibrin. Slight digestive reaction was produced by 

 fluid from ovarian cysts, but not by amniotic fluid or neutral salt used as con- 

 trols. This indicates that ovulation is not entirely a mechanical process but is 

 aided by the digestive action of the liquor folliculi. 



Studies on the mammary gland, I, II, III, J. A. Myeks (Amcr. Jour. 

 Anat., 19 (1916), No. S, pp. 353-389. figs. 17; 22 (1917), No. 2, pp. 195-223, figs. 

 12; Anat. Rec., 13 (1917), No. 4, pp. 205-226, figs. 7).— These anatomical studies 

 were initiated to provide a basis for various lines of experimental work on the 

 mammary gland. The albino rat was the laboratory form selected for study. 



I. The groicth and distribution of the milk-duds and the development of the 

 7iipple in the albino rat from birth to ten weeks of age. — The methods used in- 

 cluded serial sections, wax reconstructions, and the whole amounts stained and 

 cleared after the methods of Lane-Claypon and Starling (E. S. EL, 18, p. 75). 



