REPRODUCTIVE ELEMENTS IN APUS AND BRANCHIPUS. 269 



with others, like those of Salamander, in which the chromatin 

 is arranged in a succession of bands or irregular annuli, set 

 more or less transversely to the long nuclear axis. These 

 appearances would be produced by a similar fusion of globules, 

 in such a manner that a fevf diaphragm-like membranes of the 

 intervening fluid with its staining microsomes were left across 

 the long axis of the nucleus. In such a case the chromatin 

 would inevitably be arranged as it always is in the re-entrant 

 solid angles. Interesting artificial reproductions of the nuclear 

 figures may be seen by watching the growth of bubbles, and 

 I have given in fig. 18 some drawings of the ultimate con- 

 figurations produced by the growth of bubbles in a fine froth. 

 The lines of foam left as bands along the position of the 

 ruptured walls would represent the chromatic loops, and it 

 will be seen that they show a marked tendency to contract into 

 more or less rounded bodies. 



The existence of nuclei in groups of four or five, each with 

 their ten dumb-bell chromosomes, gives a very striking appear- 

 ance to the testes of Branchipus (fig. 21) ; and while the con- 

 dition characterises one of the longest phases of the whole 

 nuclear division, its final metamorphosis occurs with the 

 utmost rapidity, the cells appearing as if transformed by magic 

 into a complete spindle figure. Intermediate phases are, how- 

 ever, to be found, and it appears that the fusion or running 

 together of the globules continues, breaking through the old 

 nuclear boundary at several points into the surrounding kyto- 

 plasmic network (fig. 8), so that the clear mass of nuclear 

 plasm appears to spread out on all sides (figs. 8, 11, 19). 

 The result of this is that chromosomes are at last left 

 hanging in a clear central space by a few irregular strands 

 of this kytoplasmic network, into which the fusion has not 

 yet broken (figs. 10 — 12, 19). These irregular strands are 

 ultimately reduced to fine threads (figs. 11, 12, 17, 19), 

 and their peripheral extremities are related to dark bodies 

 which can be nothing but the pseudosomes of which I have 

 already spoken in an earlier phase of the metamorphosis (figs. 

 10, 11, 12, da.). These pseudosomes appear now to have 



