452 SUMMARY OF CURRENT RESEARCHES RELATING TO 



the discharge of the Hquor folllcnh. But Schochet has been able to 

 supplement this view of ovulation by evidence showing that the rupture 

 of the Graafian follicle is due in part to the digestion of the theca 

 follicLili bj a proteolytic ferment in the liquor folliculi. 



Implantation and Early Segmentation of Opossum Ovum.* — 

 Charles H. Spurgeon and Ralph J. Brooks have studied this in 

 Dklelpliys virginiana. The ovum proper makes up a relatively small 

 amount of the complete Qgg. Its cytoplasm is coarse, granular, and 

 much vacuolated. The q^^ envelopes are divided into two or more 

 distinct areas. The central one which immediately surrounds the Q^g 

 is composed of many concentric, coarse, reticular layers. The peripheral 

 area is finely reticular, and the layers are not well defined. 



Selenka stated that the ovum of the opossum is intermediate in 

 type between the meroblastic and holoblastic egg. The authors point 

 out that it is difficult to understand this statement unless it refers to 

 the yolk extrusions and the agg envelopes. There are extrusions of 

 yolk given off before the agg begins to segment. The egg proper is 

 holoblastic. The egg envelopes probably correspond to the accessory 

 envelopes of the hen's egg. The extrusions of yolk or cytoplasm lie 

 around the blastomeres : they do not take any nuclear stain ; they aie 

 probably re-absorbed as food. 



The ovum shows marked polarity. The first and second polar 

 bodies are sometimes evident. The blastomeres do not adhere closely. 

 There is much mortality in the developing ova, and there are always 

 more ova in the uteri than there are embryos in the marsupium. 



Influence of Pituitary feeding" on Growth and Sexual Develop- 

 ment.! — Emil Goetsch has experimented with rats. Dried pituitary 

 extract from both anterior and posterior lobes of the gland hastens the 

 growth and development of the ovaries and testes. It also increases the 

 functional activity. Feeding with anterior lobe extract causes increased 

 weight and greater and more vigorous body-growth and development. 

 Posterior lobe extract, however, has a retarding influence. Ovarian 

 extract (corpus luteum) has a stimulating influence upon the female 

 sexual development, but retards that of the male. 



Inter-relations of Mesonephros and other Organs.^ — J. L. Bremer 

 divides Mammalian emijryos into two groups ; those which retain 

 functional Wolffian bodies (acting as glands of urinary excretion) until 

 the kidneys are sufficiently developed to excrete urine, as is the case in 

 birds and reptiles, and those in which the Wolffian bodies degenerate 

 before the kidneys reach functioning capacity. The first group includes 

 the pig, sheep, and cat ; the second, the rabbit, guinea-pig, man and 

 rat. Within each of these groups individual animals show great 

 differences in the size and presumable excretory capacity of the 

 Wolffian body or mesonephros, without regard to its duration. 



* Anat. Record, x. (1916) pp. 385-95 (15 figs.). 



t Bull. Johns Hopkins Hospital, xxvii. (1916) pp. 29-50 (13 figs.). 



X Amer. Journ. Anat. , xix. (1916) pp. 179-209 (2 pis.). 



