. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 408 ELMER L. SHAFFER. is present an unpaired sex element (Figs. I and 2). One pair of the complex is strikingly larger than the rest, being in the form of somewhat curved rods (Text-fig, i). This pair corresponds to the " macrochromosome" pair described by Kornhauser ('14) in Enchenopa. Two other chromosome pairs (BB, CC, Text-fig, i) can also be distinguished from the other chromosomes by their size, being approximately half the size of the macro-chromosomes (AA). The other 13 chromosomes show no size differences
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 408 ELMER L. SHAFFER. is present an unpaired sex element (Figs. I and 2). One pair of the complex is strikingly larger than the rest, being in the form of somewhat curved rods (Text-fig, i). This pair corresponds to the " macrochromosome" pair described by Kornhauser ('14) in Enchenopa. Two other chromosome pairs (BB, CC, Text-fig, i) can also be distinguished from the other chromosomes by their size, being approximately half the size of the macro-chromosomes (AA). The other 13 chromosomes show no size differences which would enable us to arrange them in pairs or distinguish. TEXT-FIG, i. Spermatogonial chromosomes, showing the relative sizes of the chromosomes; the macrochromosome pair, A A, the BB and CC pairs, and 13 other chromosomes which show no size differences. them from each other. However, as will be later shown, the AA, BB, and CC chromosome pairs are so characteristic in their form and size that they can be recognized in all the diploid groups. The size relations of the chromosomes of Cicada corre- spond to those described by Kornhauser ('14) in Enchenopa. Also in the Cercopidce (Homoptera), Boring ('13) has described three pairs of chromosomes (A, B, C) which bear similar size relations to the three pairs here described in Cicada. The sex-chromosome cannot be identified in the spermatogonial groups either by its size nor by any peculiarities in its staining reactions. In the resting spermatogonia there is, however, always present a single chromatin nucleolus (Fig. 13) which probably is the persisting sex chromosome. (b) Ovarian Follicle Cells.—Among the follicle-cells of the ovary, mitotic figures are very abundant. I have found a great many mitoses not only among the follicle-cells surrounding the young growing oocytes, but even among the follicle-cells sur- rounding the almost mature oocytes. I have searched for evi- dences of amitotic division among these cells, which h
Size: 3752px × 666px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
