. The cell in development and inheritance. Cells. 184 FERTILIZATION OF THE OVUM These discoveries were confirmed and extended in the case of Ascaris by Boveri and by Van Beneden himself in 1887 and 1888 and in several other nematodes by Carnoy in 1887. Carnoy found the number of chromosomes derived from each sex to be in Coronilla 4, in OpJiiostoimim 6, and in Filaroides 8. A little later Boveri ('90) showed that the law of numerical equality of the paternal and maternal chromosomes held good for other groups of animals, being in the sea-urchin Echinus 9, in the worm Sagitta 9, in the medusa T
. The cell in development and inheritance. Cells. 184 FERTILIZATION OF THE OVUM These discoveries were confirmed and extended in the case of Ascaris by Boveri and by Van Beneden himself in 1887 and 1888 and in several other nematodes by Carnoy in 1887. Carnoy found the number of chromosomes derived from each sex to be in Coronilla 4, in OpJiiostoimim 6, and in Filaroides 8. A little later Boveri ('90) showed that the law of numerical equality of the paternal and maternal chromosomes held good for other groups of animals, being in the sea-urchin Echinus 9, in the worm Sagitta 9, in the medusa Tiara 14, and in the mollusk PterotracJica 16 from each sex. Similar results were obtained in other animals and in plants, as first shown by Guignard in the lily ('91), where each sex contributes 12 A ^ Fig. 91. — Germ-nuclei and chromosomes in the eggs of nematodes. [Carnoy.] A. Egg of nematode parasitic in Scyllium ; the two germ-nuclei in apposition, each containing four chromosomes; the two polar bodies above. B. Egg of Filaroides; each germ-nucleus with eight chromosomes; polar bodies above, deutoplasm-spheres below. In the onion the number is 8 (Strasburger); in the annelid Ophryo- trocha it is only 2 from each sex (Korschelt). In all these cases the number contributed by each is one-ha/f the jwniber characteristic of the body-cells. The union of two germ-cells thus restores the normal number, and here we find the explanation of the remarkable fact commented on at page 67 that the njiniber of chromosomes in sexually prodjiced organis^ns is alzvays even} These remarkable facts demonstrate the two germ-nuclei to be in a morphological sense precisely equivalent, and they not only lend very strong support to Hertwig's identification of the nucleus as the bearer of hereditary qualities, but indicate further that these qualities 1 Cf. p. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability
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