THE BEHAVIOR OF THE CHROMOSOMES IN 
OENOTHERA LATAXO. GIGAS 
OCNTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 128 
REGINALD RUGGLES GATES_ 
(WITH PLATES XII—XIV) 
The hybrid which forms the subject of this paper is of peculiar 
interest because one of its parents has double the number of chromo- 
somes possessed by the other, O. Jata having usually 14 chromosomes 
and O. gigas 28. Very few cases of this sort are known, either in 
plants or animals. But a further complication arises in the fact 
that O. gigas is known to have originated from O. Lamarckiana, 
which also has 14 chromosomes, and O. gigas has in all probability 
attained the tetraploid number by a duplication of the chromosome 
set present in O. Lamarckiana.:_ Then if fertilization took place in 
the ordinary manner, the hybrid O. lataX O. gigas would be expected 
to have 21 chromosomes, 7 derived from the lata egg and 14 (which 
is probably a double set of Lamarckiana chromosomes) derived from 
the male cell of gigas. Under these circumstances, the behavior of 
the chromosomes in the hybrid, especially during the period of reduc- 
tion and germ-cell formation, is a matter of especial interest. 
The general results regarding chromosome numbers and distri- 
bution were obtained some time ago, and a brief statement was pub- 
lished (10), but the cytological evidence is here presented for the 
larger ones, there has been a transverse split of the D. rotundifolia ch 
179] [Botanical 
