RIPE OVARIAN OVUM. 219 



"The inner mass which up to this time has remained compact now 

 breaks up into separate highly refractive bodies, of spherical or angular 

 form and of very different sizes ; between them, here and there, are scattered 



drops of a fluid fat I am very much inclined to regard the solid bodies 



in question as fat or as that peculiar modification of albuminoid bodies 

 which we recognise as the certain forerunner of the formation of fat in so 

 many pathologically altered tissues; and therefore to refer the disappearance 

 of the germinal vesicle to a fatty degeneration. On one occasion I believe 

 that I observed an opening in the membrane at this stage ; if this is a 

 normal condition it would be possible to believe that its solid contents 

 passed out and were taken up in the surrounding plasma. What becomes 

 of the membrane I am unable to say; in any case the germinal vesicle has 

 vanished to the very last trace before impregnation occurs." 



Kleinenberg clearly finds that the germinal vesicle disappears 

 completely before the appearance of the Richtungskorper, in 

 which he states a pseudocell or yolk-sphere is usually found. 



The connection between the Richtungskorper and the germi- 

 nal vesicle is not a result of strict observation, and there can be 

 no question that the evidence in the case of invertebrates tends 

 to prove that the germinal vesicle in no case disappears owing 

 to its extrusion from the egg, but that if part of it is extruded 

 from the egg as Richtungskorper this occurs when its constituents 

 can no longer be distinguished from the remainder of the yolk. 

 This is clearly the case in Hydra, where, as stated above, one of 

 the pseudocells or yolk-spheres is usually found imbedded in 

 the Richtungskorper. 



My observations on the Skate tend to shew that, in its case, 

 the membrane of the germinal vesicle is extruded from the egg, 

 though they do not certainly prove this. That conclusion is 

 however supported by the observations of Schenk 1 . He found 

 in the impregnated, but not yet segmented, germinal disc a 

 cavity which, as he suggests, might well have been occupied by 

 the germinal vesicle. It is not unreasonable to suppose that 

 the membrane, being composed of formed matter and able only 

 to take a passive share in vital functions, could, without thereby 

 influencing the constitution of the ovum, be ejected. 



If we suppose, and this is not contradicted by observation, 

 that the Richtungskorper is either only the metamorphosed 

 membrane of the germinal vesicle with parts of the yolk, or part 

 of the yolk alone, and assume that in Oellacher's observations 



1 "Die Eier von Raja quadrimaculata,'' Sitz. der k. Akad. W ten, Bd. LXVIII. 



152 



