670 EXPERIMENT STATION RECOED. 



during gestation : The first or kinetic, when the cells are i-apidly formed, and 

 which is determined by the secretion of the corpus luteum, and the second or 

 glandular phase, which is conditioned by some other factor. 



The spermatogenesis of the domestic guinea (Numida meleagris), M. F. 

 GuYER {Anat. Anz., 3-', {1909), No. 20-21, pp. 502-513, pis. 2).— The author finds 

 that although there are several departures from those recorded for the sperma- 

 togenesis of most vertebrates, the general order and most of the minor details 

 with guinea fowl are similar to those of the pigeon previously determined, 

 including the double numerical reduction from the spermatogonia! number of 

 chromosomes brought about through a pairing of the chromosomes both in the 

 primary and secondary spermatocytes. 



An important point determined was the existence of an accessory chromo- 

 some common to insects, which possibly has some bearing on the determination 

 of sex. Seventeen chromosomes differing in size occurred in the spermatogonia. 

 Kine appear for division in the primary spermatocytes, of which 8 are pre- 

 sumably bivalent, the other being accessory and passing undivided to one pole 

 of the spindle in advance of the others. "At the division of the secondary 

 spermatocyte the odd chromosome after lagging for some time divides longi- 

 tudinally. The divisions of the secondary spermatocytes result in the produc- 

 tion in equal numbers of 2 classes of spermatids, those containing the odd 

 chromosome and those without it. The two kinds of spermatids are visibly 

 different and ultimately give rise to spermatozoa which differ in size." 



The spermatogenesis of the domestic chicken (Gallus gallus), M. F. Guyer 

 (A)wt. Ahz., 3-'f {1909), Xo. 22-2.'/ . pp. 513-580, pis. 2).^Iu the spermatogenesis 

 of the chick, as in that of the guinea, there is an accessory chromosome, a double 

 numerical reduction to one-fourth the spermatogonial number of chromosomes, 

 and two sizes of spermatozoa. In the first division of the spermatocytes the odd 

 chromosome not infrequently reveals a tripartite structure. Often one of its 

 components seems to stand more or less apart and behaves much after the man- 

 ner of a supernumerary chromosome. The odd chromosome passes undivided 

 to one pole in the vast majority of cases. Tlius one daughter cell receives 8, the 

 other 9 chromosomes. The final result of the two divisions of the spermatocytes 

 is the production of 4 spermatids, two of which receive 4, and two 5 chro- 

 mosomes. 



Parthenogenetic segmentation in birds, A. Lecaillon {Compt. Rend. Acad. 

 Sci. [Paris], V,8 {1909), No. 1, pp. 52, 58; Compt. Rend. Soc. Biol. [Paris], 66 

 (1909), No. 23, pp. 1053-1055; abs. in Jour. Roy. Micros. Soc. [London], 1909, 

 No. Jf, p. Ji'iJ). — The author has observed a true parthenogenetic cleavage in 

 unfertilized eggs of the fowl. Mitosis appears to be abnormal, as it affects only 

 a part of the cicatricula, proceeds more slowly than in fertilized eggs, and the 

 cells gradually degenerate. The segmentation of parthenogenetic eggs appears 

 to be similar to that of eggs fertilized by weakened spermatozoa, which occurs 

 when tlie males have been removed from the breeding pen for some time. 



Studies on the physiology of reproduction in the domestic fowl. A case 

 of incomplete h.ermaph.roditism, R. Pearl and Maynie R. Curtis {Biol. Bui. 

 Mar. Biol. Lah. Woods Hole, 17 {1909), No. J,, pp. 271-283, pis. 2, fig. 1).—The 

 authors describe a Barred Plymouth Rock bird which externally resembled a 

 normal hen, although the comb and wattles were abnormally large, a condition 

 similar to the antero-posterior gynandromorphism of insects. " Internally the 

 bird possessed on the left side a large, lobulated gland in the position and 

 anatomical relations normal to the ovary. There was also a fully developed, 

 normal oviduct, in functional condition on the left side of the body. On the 

 right side of the body was a small organ in the position and anatomical rela- 



