. Carnegie Institution of Washington publication. !/.*(»â ,';â â '"â¢'. Fig. 67.âDiagrams comparing gastiulae of Chimaera and Selachian. A and />', Earlier and later stages in gaslrula of Chimaera colliei. Tand D, Earlier and later gastrulae of shark (mainly after Ruckerl). ". Archenteron. 'i'» Dorsal lip of blastopore. »''. Segmentation cavity. I'l, Ventral lip of blastopore. fails to appear within the blastodermal disc, since here it has long been functionless. But obviously the blastopore would again become important in the economy of f^astrulation, if nutritive material wer
. Carnegie Institution of Washington publication. !/.*(»â ,';â â '"â¢'. Fig. 67.âDiagrams comparing gastiulae of Chimaera and Selachian. A and />', Earlier and later stages in gaslrula of Chimaera colliei. Tand D, Earlier and later gastrulae of shark (mainly after Ruckerl). ". Archenteron. 'i'» Dorsal lip of blastopore. »''. Segmentation cavity. I'l, Ventral lip of blastopore. fails to appear within the blastodermal disc, since here it has long been functionless. But obviously the blastopore would again become important in the economy of f^astrulation, if nutritive material were brought into its neighborhood by any process in the growth of the blastoderm or in the encroachment of the germinal wall. Thus we may infer that it would again become a functional organ when its position was transferred to the rim of the blastoderm. In this position it still occurs exceptionall5^ as C. K. Hoffman has shown in Acanthias, * or it maj' indeed reopen deeper under the rim of the blastoderm, as the majority of investigators maintain. * In a letter, which I am permitted to quote (July, 1903), from Professor Hoffman, the comparison is accepted as follows: "In Chimaera the blastopore is located near and in Acanthias «/ the rim of the early blastoderm. For the rest the archenteron and the open blastopore of Acanthias agree entirely with those of Chimaera. Acanthias forms the bridge (in this regard) between Chimaera and other sharks and furnishes us the key to the problem of gastrulation of the other ;. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Carnegie Institution of Washington. Washington, Carnegie Institution of Washington
Size: 3213px × 778px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorcarnegie, bookcentury1900, bookdecade1900, bookyear1906
