. Cytology, with special reference to the metazoan nucleus. Cells. 126 CYTOLOGY CHAP. The paired arrangement of homologous chromosomes is most strik- ingly shown in the Diptera (Metz, 1916), in some species of which homo- logous chromosomes are very closely approximated. This culminates in Culex, where they are often so closely applied to one another as to be distinguished only with difficulty. Fig. 56 shows the chromosome. Fig. 56. The chromosomes of Culex as figured by different workers, showing the close approximation of homologous chromosomes. (A, B, from Stevens, , 1910 ; C, from Ta
. Cytology, with special reference to the metazoan nucleus. Cells. 126 CYTOLOGY CHAP. The paired arrangement of homologous chromosomes is most strik- ingly shown in the Diptera (Metz, 1916), in some species of which homo- logous chromosomes are very closely approximated. This culminates in Culex, where they are often so closely applied to one another as to be distinguished only with difficulty. Fig. 56 shows the chromosome. Fig. 56. The chromosomes of Culex as figured by different workers, showing the close approximation of homologous chromosomes. (A, B, from Stevens, , 1910 ; C, from Taylor, , 1915 ; D, E, from Whiting, , 1917 ; F, G., from Hance, , 1917; H, I, J, from Metz, , 1916.) A, spermatogonial pro- phase ; only one of the three chromatin threads is visibly double ; B, spermatogonial metaphase, three pairs of separate chromosomes; C, somatic prophase; D, spermatogonial prophase ; E, spermatogonial anaphase; F, ovarian (diploid) prophase; G, spermatogonial metaphase; H, I, J, prophase, metaphase, and anaphase of somatic mitoses. complex of this mosquito (where 2n = 6) as depicted by various workers. As will be seen, the homologous chromosomes in prophase (Fig. 56, A, C, D, F, H) are generally intimately applied to or twisted round one another, quite as closely as are the daughter halves of split prophase chromosomes in the somatic mitoses of many other forms (Figs. 3, 8).. 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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