ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1884.tb02047.x

出版商:Blackwell Publishing Ltd    

年代:1884

数据来源: WILEY

ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1884.tb02048.x

出版商:Blackwell Publishing Ltd    

年代:1884

数据来源: WILEY

摘要:

Summary.The egg of Trachinus is about 1.32 millim. in diameter, and contains from 20 to 30 small oil‐globules, thus differing from the majority of floating fish eggs hitherto described.In the unfertilized egg a vitelline membrane is easily distinguishable, but afterwards this comes in close contact with the zona radiata, and often requires the action of reagents to show it properly.My observations appear to confirm those of Henneguy, that the invagination observed in optic section in the living egg is an inward folding of the lower layer cells of the epiblast, and that afterwards the alimentary tract is built up from this layer, together with material derived from the intermediary layer. This point cannot, however, be settled definitely without a careful examination of sections of this stage.My observations confirm those of Ryder as to the nature and persistence of the segmentation‐cavity, and in this respect pelagic teleostean eggs seem to differ from all others hitherto described.Although the heart appears early on the fourth day, its venous end remains closely applied to the vitellus up to several days after hatching, and I have not been able to find any vascular system either in the embryo or in the vitellus up to 14 or 15 days after development begins, that is 4 or 5 days after hatching. In this respect the observations of Ryder and Kingsley and Conn agree with my own, although in non‐pelagic teleostean eggs an elaborate circulatory system is developed both in the vitellus and in the embryo a considerable time before hatching.I have nothing new to record in the later stages of development. The liver and the pancreas arise as little pouches budded off from the mesenteron; the proctodeum arises late, but is well formed at the time of hatching. The stomodeum does not appear to develop until the embryo has left the shell. The young fish usually hatch out on the tenth or eleventh day after impregnation, the early ones with little pigment on the eyes and body, the later ones with the pigment much more deve

ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1884.tb02049.x

出版商:Blackwell Publishing Ltd    

年代:1884

数据来源: WILEY