THE ANNALS 



AND 



MAGAZINE OF NATURAL HISTOEY. 



[FIFTH SERIES.] 



" per litora spargite museum, 



Naiadea, et ciroum vitreoa oonsidite fontes: 

 PoUiee virgineo teneros hie carpite flores : 

 Floribus et piotum, divae, replete eanistrum. 

 At vos, o Nymphae Craterides, ite sub undas ; 

 Ite, reourvato variata corallia trunco 

 Vellite museosis e rupibus, et mihi conchas 

 Ferte, Deae pelagi, et pingui conchylia succo." 



iV. Parthenii Gianneftasii Eel . 1 . 



No. 115. JULY 1887. 



I. — The Significance of the Yolk in the Eggs of Osseous 

 Fishes. By Edwaed E. Pkince, St. Andrews Marine 

 Laboratory. 



[Plate II.] 



Much has been recently written upon the relation of the food- 

 yolk and the germ in Teleostean eggs, yet little unanimity 

 seems to characterize the conclusions reached by various 

 observers. It is generally allowed that the free margin of 

 the thickened blastodermic ring is really the lip of the blasto- 

 pore — the entire periphery being so, and not merely, as Mr. 

 Cunningham has ably shown *, an invaginated arc, as in the 

 Elasmobranchs. The difference of opinion that exists arises, 

 however, from the various views held as to the nature of the 

 yolk and its function during development. Hackel, from his 

 study of a pelagic ovum, concluded that the yolk in Tele- 

 ostean eggs was emphatically distinct from the germ f, a con- 

 trast in the main constituents of the egg that M. Coste seems 

 to have first truly signalized if. Later investigators (Klein, 



* Quart. Jouvn. Microsc. Sci., Nov. 1885. 



t Jenaisclie Zeitschr. vol. ix. 1875. 



X Gazette m6dic. de Paris,' No. 17, 1855, p. 257, 



Ann. & Mag. N. Hist. Ser, 5. Vol. xx. 1 



