Contributions from the Zoological Laboratory Volume 8

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated.1902 Excerpt: ... Ueberaetxungsrecht vorbehalten. The Spermatogenesis of Peripatus (Peripatopsis) balfouri up to the Formation of the Spermatid. By Thos. H. Montgomery jr., Ph. D., Assistant-Professor of Zoology, University of Pennsylvania, Philadelphia, U. 8. A. With Plates 19--25. Contents. Introduction. I. Material. IT. Structure of the male genital organs. 1. Testis. a) Sheath of the testis. b) Fibre-cells of testis. c) Distal end of testis. 2. The seminal vesicle. 3. The vas deferens. III. Spermatogonia and their mitoses. 1. Best stage. 2. Mitosis up to the metakinesis. 3. Metakinesis. IV. Anaphases of the last spermatogonic mitoses. 1. Early anaphases. 2. Synapsis stages. 3. Telophases. V. Rest stage of the spermatocytes. VI. Maturation mitoses. 1. Prophases. a) Idiozome and centrosomes. b) Nucleus. 2. Monaster stage of the 1st spermatocytes. 3. Metakinesis and dyaster of the 1st spermatocytes. 4. Second maturation mitosis. 5. Structure of the spermatozoon. VII. The giant spermatogonia. VIII. Number of chromosomes in cells not of the spermatogenetic series. IX. General part. 1. Relations of chromatin and linin; the chromosome concept; individuality of chromosomes. 2. Movements of the chromatin. 3. Polarity of nucleus and cell body. 4. The synapsis stage. Literature list. Explanation of plates 19--25. Introduction. The present study was undertaken with two main objects in view. First, to find whether or not Peripatus, which is generally held to be in the ancestral line of Insects, would show a type of spermatogenesis similar to that of Insects. And second, to determine whether in Peripatus there would be a clue to the mode of origin of that curious metamorphosed chromosome, first fully described by me for Pentatoma, and termed the chromatin nucleolus. My work has shown...