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SUMMARY OF CURRENT RESEARCHES RELATING TO 
left, and forms the endoderm. But the two rows of cells beneath the 
original covering cells curve to right and left, and form the mesoderm. 
The notochord is constricted off, first from the covering cells, then from 
the endoderm. Where the duplication of rows of cells begins, is not the 
blastopore, but the beginning of the notochord. The blastopore lies 
where the duplication of cell-rows ends, i.e. at the end of the notochord. 
Keeping pace with the development of the germinal layers, the notochord 
comes to lie along the embryo between the two mesoderm plates. 
Origin and History of the Graafian Follicle.* — Dr. J. Schottlaender 
has investigated the ovaries of the cat, rabbit, pig, &c., and has com- 
pared them with the human ovary. In the human ovary, ova and 
follicular epithelium arise directly from the germinal epithelium. 
Waldeyer’s Eiballen are first formed. From these, with increased 
growth of connective tissue, there arise (a) the Pfliiger-Valentin tubules, 
( b ) the typical primordial follicles, (c) atypical primordial follicles, 
with two or three ova (which secondarily become primordial), ( d ) Eibal- 
lenfollikel , which arise by connective delimitation of larger or smaller 
portions of the Eiballen and modification of these into follicles, and 
(e) tubular follicles which arise by connective delimitation of larger or 
smaller parts of (a). It seems likely that most, if not all, of the larger 
follicles in the ovary of a child are Eiballen- or tubule-follicles ; these 
are rapidly formed, and that they may represent an organic economy 
the author explains. He gives a decided negative answer to the question 
whether new Graafian follicles arise in the adult human ovary. The 
unchanged Graafian follicle is described in detail, as regards ovum, 
follicular epithelium, and theca folliculi. 
The degeneration of an unburst follicle (follicular atresia) is a 
physiological process, whose chief criterion is to be found in the state 
of the follicular ovum. The state of the follicular epithelium is less 
important, for the epithelium always degenerates in the formation of the 
liquor. In the ovum and in epithelial cells, the nucleus undergoes (a) 
chromatolysis or (6) atrophy, the cell-substance exhibits degeneration 
either fatty (a) or otherwise (/ 3 ) (perhaps albuminous ?). There are 
various combinations of (a) and (b) with (a) and (/ 3 ). The effect of (a) 
and (j8) is to liquefy the cell-substance which seems to lead to hyaline 
coagulation of the ovum. Even the primitive ova may exhibit degenera- 
tion. The corpus luteum arises without the participation of epithelial or 
wandering cells by the proliferation of the epithelioid cells of the theca 
interna of a follicle which is ready to burst. 
Placenta of Rodents.f — Dr. A. Fleischmann has succeeded in 
demonstrating the uniformity of placentation in the Rodentia. He has 
previously shown that the so-called “ inversion ” in mouse and guinea- 
pig can be harmonized with what occurs in rabbit and porcupine. He 
has now succeeded in harmonizing the varied relations of the blasto- 
dermic vesicle to the lumen of the uterus. A study of Spermophilus 
citillus has enabled him to connect the state of affairs in Lepus and 
Sciurus with that in Mus, Cricetus , Arvicola , and Cavia. In all cases, 
what may be called the prodiscoidal type is demonstrable. The techni- 
* Arch. f. Mikr. Anat., xli. (1893) pp. 219-94 (2 pis.). 
f SB. K. Preuss. Akad. d. Wiss., 1892, pp. 445-57 (1 pi.). 
