. Cytology, with special reference to the metazoan nucleus. Cells. V CONTINUITY OF THE CHROMOSOMES The grouping of the chromosomes derived from the male and female parents which is to be seen in the first few cleavage divisions is of course an example of gonomery, such as occurs in Cyclops, etc. (Fig. 35), and, as usual, disappears in later cleavages. The important fact is that the two types of chromosomes introduced by the two parents, though mingled together, are recognizable in all mitoses. From this we conclude that their loss of identity in the resting nucleus is apparent only, and not re
. Cytology, with special reference to the metazoan nucleus. Cells. V CONTINUITY OF THE CHROMOSOMES The grouping of the chromosomes derived from the male and female parents which is to be seen in the first few cleavage divisions is of course an example of gonomery, such as occurs in Cyclops, etc. (Fig. 35), and, as usual, disappears in later cleavages. The important fact is that the two types of chromosomes introduced by the two parents, though mingled together, are recognizable in all mitoses. From this we conclude that their loss of identity in the resting nucleus is apparent only, and not real. In the Lepidopteran cross Lycia hirtaria x Ithysia zonaria (Harrison. Fig. 63. Fertilization of the egg of Ascaris megalocephala bivalens by spermatozoa of A. m. univalens. (After Herla, , 1895.) A, approach of the gamete nuclei; B, the chromosomes of the zygote nucleus; C, egg divided into two blastomeres ; D, twelve blastomeres. and Doncaster, 1914) the large chromosomes of Lycia and the small ones of Ithysia are distinguishable in the hybrid right up to the formation of its gametes (Fig. 185). I The persistence of an unusual number, though not of distinct types, of chromosomes in a hybrid was observed by Herla in 1895. He found five females of Ascaris megalocephala bivalens which had been fertilized by the univalens variety. Consequently the nuclei of their hybrid embryos had three chromosomes, two derived from the female and one from the. 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 Agar, W. E. (Wilfred Eade), 1882-1951. London, Macmillan and Co. , limited
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