Archive image from page 30 of Cytology, with special reference to. Cytology, with special reference to the metazoan nucleus cytologywithspec00agar_0 Year: 1920 I THE CHROMOSOMES 15 nucleus is formed by the intertwining of these threads, which at the same time become irregular and broken up (as regards the chromatin ; the linin basis of the threads remains continuous) and connected with each other by anastomoses. Prophase consists of the reverse process. There are two variations on this view : (a) Two threads are formed from each chromosome, and hence the prophase chromosomes are from the fir
Archive image from page 30 of Cytology, with special reference to. Cytology, with special reference to the metazoan nucleus cytologywithspec00agar_0 Year: 1920 I THE CHROMOSOMES 15 nucleus is formed by the intertwining of these threads, which at the same time become irregular and broken up (as regards the chromatin ; the linin basis of the threads remains continuous) and connected with each other by anastomoses. Prophase consists of the reverse process. There are two variations on this view : (a) Two threads are formed from each chromosome, and hence the prophase chromosomes are from the first double, and even the resting nucleus is duplex as regards its chromatin constituents. According to this view, therefore, the real division of the chromosomes into daughter chromosomes takes place not in prophase but in the previous telophase Fig. 7. Larva of Salamandra maculosa. (A, B, after Kowalski, , 1904 ; C, D, after Schneider, R. Hertwig, 1910.) A, C, telophase; B, D, prophase. or anaphase. This view is held by many workers, Schneider (1910), Salamandra (Fig. 7) ; Dehorne (1911), Salamandra and (1911) Allium (Fig. 8), with, however, a different interpretation as to the part played by the anaphase division in the following mitosis; Lundegardh (1913), Allium ; Schustow (1913), Allium. (b) Only one thread is normally produced from each chromosome in telophase, the division of the chromosomes taking place in prophase. [Bonnevie (1908), Ascaris (Fig. 6) and Allium (Fig. 8) ; Boveri (1909), Ascaris, exceptionally ; Vejdovsky (1911), Ascaris.] It is clear that where different workers base such contradictory conclusions on identical material, the reason for their differences must be sought largely in the difficulty of interpreting these confused stages,
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