540 
H. Iv'UGGLES GATES AND NESTA THOMAS. 
This division of what is presumably the extra chromosome 
on the heterotypic spindle is often not a regular one, but 
consists in an irregular pulling apart of the chromosome into 
tAvo, or sometimes a fragmentation into three parts. More- 
over, this behaviour is not always confined to a single 
chromosome, for occasionally two chromosomes may be seen 
to divide on the same heterotypic spindle, and this condition 
has even been found in a Lamarckiana plant derived from 
semilata. Hence, assuming that this peculiarity of dividing 
in the first division is characteristic of the extra chromosome, 
it cannot be confined entirely to that chromosome, but some- 
times extends to one of the others. This behaviour has never 
been found, however, in pure races of Lamarckiana or its 
mutants having 14 chromosomes, so that it appears to be 
connected with peculiarities and disturbances arising originally 
from the presence of the extra chromosome. 
CR. MUT. LATA EUBEICALYX. 
Returning now to the detailed description, we shall first 
describe the phenomena of meiosis as regards the history and 
fate of the chromosomes in lata rubri calyx. The histoiy 
of the origin of this 15-chromosome plant from hybrids of 
rubricalyx and grandiflora having 14 chromosomes has 
been referred to above (see p. 533), and will be discussed 
elsewhere (Gates, 1914). Fig. 16 is a profile view of the 
heterotypic spindle i]i a pollen mother-cell of pure rubri- 
calyx, clearly showing the 14 chromosomes. The loosely 
scattered and more or less unpaired condition of the chromo- 
somes at this time is characteristic of Hluothera. Fig. 17 
is a'polar view of the same stage, showing the same chromo- 
some number, the chromosomes occurring in several foci. 
Figs. 18 to 31 are studies of various stages in the meiotic 
divisions of lata rubricalyx. They disclose much variation 
in the behaviour of the chromosomes. 
Fig. 18 shows diakinesis in a pollen mother-cell. The 15 
chromosomes are, as usual, scattered in their arrangement. 
