696 RECORD OF CURRENT RESEARCHES RELATING TO 



B. Ovary with duct. 



1. Ovigerous surface confined to a narrow strij) of tlie wall 



of tbe ovary, or forming a duplicature of the wall, with 

 which it is in connection by narrow stripes {Scorpcena, 

 &c.). 



2. The greater part of the ovarian wall bears ova. 



a. Ova originate in irregular processes of the wall 



[Lophohrancliii, &c.). 

 h. Ova originate in definite lamellae or duplicatures of 



the ovarian wall. 



1. Lamellae parallel to long axis of ovary. 



a. Whole wall of ovary beset with lamellfe : 

 canal central {Sargus, Scomber, &c.). 



)8. Part of wall of ovary devoid of lamellge ; 

 canal lateral. (Not yet observed.) 



2. Lamellas parallel to transverse axis of ovary. 



a. With central ovarian canal {Perca, Clupea, 



&c.). 

 yS- With lateral canal (Cyprinoids, &c.). 



Beyond the secondary egg-membranes, such as the gelatinous 

 investment of the perch and allied structures, Brock considers that the 

 egg has only one egg-membrane, the zona radiata : the existence of a 

 true vitelline membrane he considers still an open question. 



The tuft-like processes (Zottchen) are merely secondary appendages 

 of the zona radiata, and have nothing to do with either the follicular 

 epithelium or with the yolk. 



The yolk presents externally a " zonoid layer," which may be 

 either entirely radially striated, or may be composed of an outer 

 striated, and an inner homogeneous layer. The germinal vesicle has, 

 except in the youngest eggs, a distinct, often somewhat crumpled, 

 membrane, to the inner side of which the germinal spots are attached 

 like knobs. 



The paper concludes with some observations and remarks on the 

 development of the egg and of the follicular epithelium. 



Evolution of the Embryo in Eggs put to incubate in warm 

 water.* — M. Dareste recalls the experiment of Reaumur, who, having 

 placed eggs to hatch in warm water at the incnbating temperature, 

 found no vestige of the embryo. He renewed these experiments, and 

 proved that the development had begun, but that the embryo had died 

 at about the thirtieth hour, and had decomposed. In one single case, 

 in which the embryo had not decomposed, it presented the monstrosity 

 called " omrplialocephalic " : the heart, which was perfectly recog- 

 nizable, was seen above the head, evidently ai-rested in its formation. 

 In the vascular area there were no traces of vessels or blood. 



Mechanical Genesis of Tooth Forms.t— In his articles on this 

 subject Mr. J. A. Ryder has made a valuable contribution to tho 



* ' Comptes Kendus,' Ixxxviii. (1879) p. 11.S8. 



t 'Proc. Acad. Nat. Sci. Philad.' (1878) p. 45; (1879) p. 47. 'Am. Nat.,' 

 xiii. (1879) p. 446. 



