Recent Papers on CEnothera Mutations. 291 
recessive; and the new characters in the mutant rubricalyx behave 
as a simple Mendelian dominant in relation to its parent rubrinervis. 
Again, gigas x Lcimarckiana according to De Vries yields an 
intermediate race which remains constant, though in some cases 
the behaviour is more variable, depending apparently on chromosome 
mechanisms. These three types of hereditary behaviour are doubt¬ 
less indicative of different types of germinal change involved in the 
origin of certain mutants, a view which is fully corroborated by the 
cytological evidence. 
As regards interspecific crosses in CEnothera, the most important 
paper which has yet appeared is that of De Vries (11) on double 
reciprocal hybrids between certain races of the Linntean species O. 
biennis and O. mnricata. In general, it was found that both 
reciprocal crosses yielded uniform but strongly patroclinous hybrid 
races which remained true in later generations. These reciprocal 
crosses, which were therefore unlike, were in 1908 reciprocally 
crossed with each other, i.e. ( biennis x mnricata ) x ( mnricata x 
biennis and ( mnricata x biennis) x (biennis x mnricata). In both 
cases the offspring were a uniform race corresponding witli the 
“outside grand-parents.” Thus (B x M) x (M x B) gave B or 
biennis, while (M x B) x (B x M) gave mnricata which remained 
constant. The double reciprocal crosses therefore gave complete 
reversion to one of the grandparents, while the characters of the 
grandfather could not be transmitted through the mother and those 
of the grandmother could not be transmitted through the father. 
Similar results were obtained in crosses between races of O. biennis 
from Holland and Illinois, also with biennis and cruciata, biennis and 
strigosa, biennis and Hookeri, and biennis and Lamarckiana. In the 
biennis-mnricata series of hybrids, what are called sesquireciprocal 
crosses were made, thus ( mnricata x biennis) x mnricata [= 
(M) B x M] and ( biennis x mnricata ) x biennis [=(B) M x B]. 
The former of these crosses is again identical with mnricata, and 
the latter with biennis. Iterative hybrids were also produced in the 
following manner: (M) B x B and B x (B) M, etc. The iterative 
hybrids were like their hybrid parent. Thus (M) B x B=(M) B 
and B x (B) M=(B) M. 
An ingenious explanation of these curious results has since 
been offered by Goldschmidt (23) whose interpretation is based on 
cytological study of these hybrids. Goldschmidt believes that a 
condition of merogony exists, the male nucleus developing in the 
cytoplasm of the egg, the nucleus of the latter degenerating. The 
cross biennis x mnricata would therefore contain in its cells a 
mnricata nucleus and biennis cytoplasm, while the cells of mnricata 
X biennis would be derived from a biennis nucleus embedded in 
mnricata cytoplasm. It is of course well known that the so-called 
“male cell” in Angiosperms is really a male nucleus which has lost 
its cytoplasm. 
If the explanation of Goldschmidt proves to be correct, then 
these hybrids will furnish conclusive proof of the predominating 
influence of the nucleus in inheritance, for in each case the hybrid 
strongly resembles the parent from which its nucleus was derived. 
Although the evidence for Goldschmidt’s view is by no means 
complete and final, yet it establishes a certain presumption in its 
favour. Among the points figured are(i.) the degeneration of one of the 
