July is, 1914 
Mutation in Egyptian Cotton 
297 
Davis (1911-1913) has sought to demonstrate experimentally that 
Oenothera Lamarckiana , which is not known to occur in the wild state 
anywhere in North America, originated as a hybrid between 0 . biennis 
and O. grandiflora. 
Gates, while holding that Oenothera Lamarckiana could not have origi¬ 
nated from a simple cross of O. biennis with 0 . grandiflora , believes that 
mutation and hybridization are associated phenomena. He says: 
Mutation in O. Lamarckiana , therefore, appears to be a condition of germinal insta¬ 
bility and not a simple process of hybrid splitting, although this condition of insta¬ 
bility has probably been brought about through previous crossing in the ancestry 
(Gates, 1911, p. 605; see also 1913a, p. 58-59). 
On the other hand, Heribert-Nilsson (1912, p. 213) concluded from 
the results of his extensive hybridization experiments with this plant 
that the mutants can all be explained as either plus or minus combina¬ 
tions of characters already present in O. Lamarckiana . In his opinion 
instability of the germ plasm does not need to be assumed, and the whole 
phenomenon of mutation should be interpreted from one standpoint—that 
of Mendelian recombinations. He further concluded (1912, p. 218) 
that the mutants are not progressive or regressive new forms origi¬ 
nated through the spontaneous appearance or disappearance of a single 
unit character—that is, through mutation in the sense of De Vries—but 
are minus combinations—that is, they have originated through the re¬ 
combination of Mendelian characters already present in the parent 
species and distributed among different individuals. 
In a recent paper, Gates (1913b) rejects these conclusions of Heribert- 
Nilsson on the ground that they are contrary to the cytological evidence 
and maintains the position (p. 298) that “mutation is an independent 
process requiring a special explanation/’ 
The preponderance of evidence points to the conclusion that hybridi¬ 
zation, possibly remote and of a complex nature, has been a factor in 
the mutability of Oenothera. On the other hand, the theory of Men¬ 
delian recombination does not afford adequate explanation of all the 
phenomena observed. 
It remains to consider the evidence that hybridization has been a 
factor in the mutability of Egyptian cotton. t The facts that hybrids 
between distinct types of cotton show great diversity in the F 2 and later 
generations and that it is difficult to obtain constant varieties by hy¬ 
bridization are well known to cotton breeders. 1 Yet, if the F 2 plants 
and their progeny during successive generations should be cross- 
1 The Foster variety is one of the few well-authenticated examples of a commercially important 
variety of known hybrid origin, having originated as the result of a cross between the Sunflower (a 
small-boiled long-staple Upland variety) and the Triumph (a large-boiled, short-staple Upland variety) 
made by Dr. D. A. Saunders. Although after several years of selection this variety has attained sufficient 
stability to warrant commercial production, the Foster variety is apparently much less uniform than the 
Yuma and other varieties of Egyptian cotton which have presumably originated by mutation. Indi¬ 
viduals having the large, broad leaves and the short fiber of the Triumph variety are still frequently 
met with. (Cook, 1912, p. 17-18; 1913a, p. 16.) 
