72 Notes on Recent Literature. 
great interest arise out of his experiments with Solatium etuberosum. 
Solatium etuberosum had been grown at Reading for more than 
twenty years, and had remained completely sterile. In 1906, 
however, Mr. Sutton obtained seed from one plant, and Dr. Salaman, 
working with plants of the same race, succeeded in making a cross. 
In the following year fertile seed was again obtained by both 
investigators. During the period of sterility, the parent plant had 
become noted for its immunity to the attacks of Phytophthora 
infestans, but a large proportion of the seedlings to which it gave 
rise were attacked by the fungus. The proportions in which the 
susceptible and immune seedlings occurred suggest that immunity 
is a recessive character; if this should prove to be the case, it is 
interesting to notice that the heterozygous parent remained immune 
as long as it was sterile. 
Solarium etuberosum presents another point of interest in that 
it is found to differ from the domestic varieties in regard to the 
dominance of certain characters. Thus, in S. etuberosum , the 
round shape of the tuber is dominant to the long shape, the shallow 
eye is dominant to the deep eye, and the white is dominant to the 
dark purple colour. In the domestic varieties exactly the reverse 
is true in each case. 
Miss Saunders’ paper on the “ Inheritance of Doubleness in 
Flowers,” deals with the production of double flowers in Petunia. 
It is found that singleness is a dominant character; cross-bred 
singles, however, when self-fertilized, produce only singles; while 
singles crossed with the pollen from doubles yield doubles in 
the first generation. It is clear that in Petunia gametogenesis is 
of the peculiar type which Miss Saunders has already shown to 
occur in the Stocks ( Matthiola ), where the factors for singleness 
and doubleness are distributed differently among the ovules and 
the pollen grains. Thus, the pollen of the singles is homogeneous 
as regards the presence of some factor necessary for the production 
of single flowers ; while, with regard to the ovules of the singles 
and the pollen of the doubles, the results obtained are such as 
would occur if either (1) the ovules were homogeneous and the 
pollen heterogeneous as regards the absence of some factor for 
singleness, or (2) the ovules were heterogeneous and the pollen 
homogeneous in respect of this factor. 
The paper by Mr. Doncaster and Mr. Marshall is concerned 
with a problem relating to the determination of sex. The opinion 
has been somewhat widely held that in mammals one ovary produces 
eggs which will give rise to females; the other, eggs which will give 
rise to males. The authors have tested this hypothesis in the case 
of the rat by performing one-sided ovariotomy upon two female 
rats. Each of these animals subsequently produced a litter of 
young, and each litter contained young of both sexes. It is clear, 
therefore, that the “ right and left ” hypothesis does not hold for 
the rat, and its definite disproof in this case detracts from the 
probability of its holding good in the case of other mammals. 
R.P.G. 
R. Madley, Steam Printer, 151, Whitfield Street, London, W. 
