. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 266 EMIL WITSCHI place ailing its periphery. The relative size differences are the same in ovocytes and spermatocytes. The fact that the individual chromo- are at least four times as voluminous in female as in male germ cells of identical stage suggests that the visible chromatin represents much more than the aggregate volume of the Seen in profile the metaphasic chromosomes appear as pairs composed of two equal elements (Figs. 7 and 8). \Yeismann and Ischikawa (1888) had seen " four double-chromatin- elements &
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 266 EMIL WITSCHI place ailing its periphery. The relative size differences are the same in ovocytes and spermatocytes. The fact that the individual chromo- are at least four times as voluminous in female as in male germ cells of identical stage suggests that the visible chromatin represents much more than the aggregate volume of the Seen in profile the metaphasic chromosomes appear as pairs composed of two equal elements (Figs. 7 and 8). \Yeismann and Ischikawa (1888) had seen " four double-chromatin- elements " in the maturation spindle of the egg, while Groom (1X()4) reports that " the number of chromatic elements varies; it appears to be commonly four or five, but, in some cases was, as far as I could make out, as many as ten or ; To prove the incorrectness of these counts we refer to the photomicrograph Fig. 10. The true number. Fir,. 10. Photomia-. of the 13 chromosomes in the first maturation spindle in the egg of Lcpas. X 1500. can be ascertained without difficulty even in properlv stained whole mounts. No heteromorphic sex chromosomes have been found in somatic or in germinal cells of either sex. Nor have we observed any indication of chromosomal regulation of either the Angiostomum- or the Iccrya- type. Even though this study does not include some of the important phases of the chromosome cycle (especially that of fertilization), the evidence obtained renders it more than probable that the goose barnacle is a primary hermaphrodite in the sense defined above. Delage (1884), G. Smith (1906), Meisenheimer (1921), and others have defended the iipinion that hermaphrodism in Cirripedia is secondary, the order having descended from gonochoristic, free-swimming ancestors. The evidence of comparative morphology has, however, been interpreted also in the tip]incite sense. The chromosomal situation is distinctly in favor ot Darwin'- ( 1S51, 1854) theory of
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
