Notes on Recent Literature. 
153 
of the chromosomes which takes place at that division, so that 
occasionally both members of one pair of chromosomes may pass 
to one daughter nucleus, leaving the sister nucleus without a 
representative of that pair. Germ-cells will thus arise lacking 
certain of the chromosomes which are present in the parental type. 
On the hypothesis that the development of certain characters is 
determined by the presence of corresponding chromatic substance, 
such irregularities in the distribution of the chromosomes would 
account for a certain class of mutation, which takes the form of the 
loss of a character which is present in the parental type. The giant 
Oenothera gigas belongs, however, to another class of mutation, in 
that it possesses twenty-eight chromosomes in the somatic cells and 
fourteen in the reduced cells, as compared with the fourteen and 
seven chromosomes which occur in the corresponding cells of the 
parent type, 0. Lamarckiana. 
A further most interesting point is brought to light by Gates’ 
observations 1 on the hybrid between 0. gigas with a form known as 
O. lata which has the same number of chromosomes as 0. Lamarckiana. 
The hybrid has of course twenty-one chromosomes. In the hetero¬ 
type division these are distributed ten to one pole, eleven to the 
other. This method of distribution is different from that which 
obtains in the hybrid between Drosera rotundifolia (2X=20 ; X=10) 
and D. longifolia (2X=40 ; X=20). The hybrid has (10 + 20)== 
30 chromosomes; Rosenberg 2 has shown that in the reduction 
division, there are ten pairs of chromosomes and ten single chromo¬ 
somes. In all probability this must be interpreted as meaning that 
ten of the langifolia chromosomes have paired with the ten rotundi- 
folia chromosomes, and will separate at metaphase; the remaining 
ten longifolia chromosomes do not pair, and are distributed somewhat 
irregularly between the daughter nuclei, or may be left behind in 
the cytoplasm. In the Oenothera hybrid on the other hand, the 
distribution is such as to suggest that pairing does take place among 
six of the seven gigas chromosomes, which are unable to find fellows 
in the series contributed by the other parent, the odd chromosome 
passing to one pole or the other according to chance. The hybrid 
produces pollen in abundance and the results of further experiments 
and observations upon the posterity of the hybrid will be looked 
forward to with great interest. 
R.P.G. 
1 “The Chromosomes of Oenothera." Science, N.S. XXVII., 
1908, p. 193. 
2 Ber. d. D. Bot. Ges., XXII., 1904, p. 47. 
