. The cell in development and inheritance. Cells. PROMOKPHOLOGICAL RELATIOXS OF CLEAVAGE 381 in the egg of the tunicate Clavelina (Fig. 177), and by Watase ('91) in the eggs of cephalopods (Fig. 178). In both these cases all the early stages of cleavage show a beautiful bilateral symmetry, and not only can the right and left halves of the segmenting egg be distin- guished with the greatest clearness, but also the anterior and poste- rior regions, and the dorsal and ventral aspects. These discoveries seemed, at first, to justify the hope that a fundamental law of develop- ment had been discover
. The cell in development and inheritance. Cells. PROMOKPHOLOGICAL RELATIOXS OF CLEAVAGE 381 in the egg of the tunicate Clavelina (Fig. 177), and by Watase ('91) in the eggs of cephalopods (Fig. 178). In both these cases all the early stages of cleavage show a beautiful bilateral symmetry, and not only can the right and left halves of the segmenting egg be distin- guished with the greatest clearness, but also the anterior and poste- rior regions, and the dorsal and ventral aspects. These discoveries seemed, at first, to justify the hope that a fundamental law of develop- ment had been discovered, and Van Beneden was thus led, as early as 1883, to express the view that the development of all bilateral animals would probably be found to agree with the frog and ascidian in respect to the relations of the first cleavage. This cleavage was soon proved to have been premature. In one series of forms, not the first but the second cleavage-plane was found a. 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 Wilson, Edmund B. (Edmund Beecher), 1856-1939. New York Macmillan
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectcells, bookyear1906
