Archive image from page 60 of Cytology, with special reference to. Cytology, with special reference to the metazoan nucleus cytologywithspec00agar_0 Year: 1920 II PARASYNDESIS AND TELOSYNDESIS 45 definitive bivalents out of the pachytene loops as depicted by Farmer and Moore. It will be noticed that the longitudinal slit, faintly visible here and there in the pachytene stage (A, and A') appears from these figures to be traceable into the slits occasionally indicated in each constituent of the bivalents, and therefore represents the division plane of the second division of the meiotic phase. I
Archive image from page 60 of Cytology, with special reference to. Cytology, with special reference to the metazoan nucleus cytologywithspec00agar_0 Year: 1920 II PARASYNDESIS AND TELOSYNDESIS 45 definitive bivalents out of the pachytene loops as depicted by Farmer and Moore. It will be noticed that the longitudinal slit, faintly visible here and there in the pachytene stage (A, and A') appears from these figures to be traceable into the slits occasionally indicated in each constituent of the bivalents, and therefore represents the division plane of the second division of the meiotic phase. It would take too much space to discuss fully the relative merits of the two theories, but the most important pros and cons can be briefly summarized, remembering that it is impossible to reconcile the divergent A' b' c' Fig. 18. Illustrating telosyndetic view of meiosis. (A-C, after Farmer and Moore, , 1905.) A-C, three stages in the formation of the bivalents in Osmunda regalis. A'-C, their interpretation according to the telo- syndetic view. Supposed points of junction of the longitudinally split constituents of each bivalent. views by the simple assumption that parasyndesis holds for some species and telosyndesis for others. For the disputed stages—zygotene and diplotene—are too similar in many of the species which have been inter- preted in opposite senses to have been brought about by such different processes, and, moreover, in many instances opposite accounts have been given of the same species. r. The overwhelming balance of evidence of actual observation appears to the author and many others (including the older cytologists who were not interested in either theory) to favour the view that the diplotene and diakinetic figures are produced by the reopening of the
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