STRUCTURE OF CERTAIN CHROMOSOMES 3 
chromatin derived from the persisting chromatin of the telo- 
phasic spirals. These spirals are therefore the rudiments of 
anew generation of chromosomes. 
K. C. Schneider (‘ Festschr. f. R. Hertwig ’, 1, 1910, p. 215) 
also describes the chromosomes of the anaphase as consisting 
of a chromatic spiral enveloping an achromatic core; but 
finds this spiral become double in the telophase. He does 
not find in the quiescent nucleus a network formed by ana- 
stomosing processes of the spirals, but only a tangle formed by 
the attenuated and elongated spirals themselves. But these 
spirals are differentiated into chromatic granules united by an 
(apparently) achromatic thread. The prophasic chromosomes 
are formed by the condensation of the granules into (two) new 
chromatic spirals enveloping this thread. 
Vejdovsky ( Zum Problem der Vererbungstriger ’, Prag, 
1912) also finds that a ‘ripe’ chromosome consists of an 
achromatic core round which is wound a chromatic fibre. To 
this fibre he gives the name of *chromonema’. He finds no 
membrane. At the telophase, the achromatic core is cast out, 
and, swelling, forms the nuclear enchylema. But the chromo- 
nema differentiates into a new achromatic thread with chroma- 
tic granules (‘ chromioles ’) imbedded in it. The threads thus 
constituted anastomose into the network of the quiescent nu- 
cleus. At the prophase the anastomoses are withdrawn, and the 
chromioles fuse into a new continuous chromonema, spirally 
coiled round the persisting threads. In the later prophase the 
chromonema segments into ‘chromomeres’ which undergo 
bipartition, and so bring about the division of the chromosomes. 
So that Vejdovsky, though a supporter of the chromonema 
theory in so far as he recognizes the chromatic thread as a 
chief constituent of the chromosome, does not entirely discard 
the granule theory of Balbiani and Pfitzner. Like Bonnevie, 
he conceives of the chromonemas as the rudiments (Ania gen) 
of a new generation of chromosomes (op. cit., p. 171. et 
passim). ; 
The alveolation theory was foreshadowed by some 
observations of van Beneden’s, but has only been worked up 
B 2 
