Prof. Valentin's Beport on the Progress of Embryology/. 369 



the interior of the germinal vesicle presents new celly, or that 

 (as was seen in the rabbit), within the germinal vesicle, new 

 cells are really built up upon the foundation of the germinal 

 spots. — {Introductory Bemarks, p. 13). 



First stages in the development of the fecundated ovum, 

 especially that of the Mannnalia. — As was already remarked in 

 the Introduction, the most important publications of the past 

 year concerning embryology, are concentrated in the subjects 

 of this chapter. We will, therefore, before presenting some 

 extracts of the details, first state the most important results. 

 With few exceptions to be mentioned, all the observations 

 have reference to the Mammalia, and indeed to the rabbit. 



1. At the period of the rut certain changes have alreadif taken 

 place in the ovarium^ the [Graafan] follicles, and the structures 

 appertaining ^/^er^/o.— Through an increased congestion of the 

 ovary single follicles become more strongly developed. The 

 germinal spot, which gives the impulse to the formation of 

 new cells, probably undergoes changes of this kind. From 

 the observations of Negries, above-mentioned (p. 248), it may 

 be conjectured that in the human female also, the period of 

 menstruation is attended by similar phenomena. 



2. Fecundation itself comes to pass apparently in the folloiv- 

 ing manner, A portion of the semen that has been brought to 

 the surface of the ovarium probably passes into the ovum, and 

 gives the stimulus to the formation of cells within the germinal 

 vesicle. ****** 



3. The nmnber of ova prepared for fecundation by the rut^ 

 does not correspond with the number of the subsequently fecun- 

 dated ova, but generally exceeds the same. — This fact, already 

 known, has been confirmed by the latest researches on the 



rabbit. 



4. // often happens that more ova pass out of the ovary than 

 are fecundated, or at least than become developed. — Herein ac- 

 cord the observations of Barry with those of Pappenheim. 

 The former found in the tubes and uterus unfecundated or 

 aborted ova. In like manner, parts of the [Graafian] follicle 

 which usually remain in the ovary, for example, portions of 

 Barry's ovisac, may be found in the oviducts. 



5. Neither the place to ivhich the ova in the tubes and uterus 

 have advanced, nor the size of the same, nor the time that has 



