STRUCTURE OF CERTAIN CHROMOSOMES 21 
signs of such a process. I need not enter into further details, as 
Schneider himself seems to have abandoned his supposition. 
For in a later work (his “ Histologische Mittheilungen”’, 11, 
‘““Chromosomengenese ”’, in ‘ Festschr. f. R. Hertwig’, 1, 1910, 
pp. 218, 219, 221) he maintains his view that a division of the 
chromosomes probably takes place at the telophase (or ana- 
phase), but now supposes it to bea longitudinal one.’ 
Of this also I find no evidence. But I do find evidence of 
another and simpler process by which the observed images of 
duplicity are brought about. To the consideration of this we 
may now proceed. 
(b) Descriptive. 
We have already seen incidentally, m Part I, that m the 
Amphibia the chromosomes of the later telophase are double 
structures, that is, that they consist of two chromatic threads, 
longitudinally collocated and more or less entwined. 
This is by no means peculiar to the Amphibia. In smaller 
chromosomes than theirs the images are more difficult ; and m 
much smaller ones it may be impossible to obtain satisfactory 
resolution. But enough can be made out to leave no doubt 
that it is a very widespread phenomenon. In the Mammalia 
T have found it fairly clear in Homo, fig. 54. In some of the 
Insecta (notably the Orthoptera) it is as certaim as m the 
Amphibia, see figs. 62, 66, 67. I thnk we may take it as the 
invariable rule that in animals all the telophase chromo- 
somes are thus doubled, that 1s, possess already the duplicity 
observed in the chromosomes of the prophase. ‘This relieves us 
from the necessity of looking for any process of splitting in the 
phases between the telophase and the prophase ; and it only 
remains for us to make out in what way the telophasic doubling 
is brought about. 
1 The reason he gives for this is a strange one. He admits (p. 218) that 
the daughter chromosomes of the metaphase only show one spiral; but 
thinks (without asserting it positively) that in the anaphase and telophase 
they contain two, because * the coils they show are so closely set that they 
could hardly be the expression of a single spiral’. How about a reel of 
cotton ? 
