1909] CURRENT LITERATURE 471 
East’? finds that dent and flint corns differ from one another in a considerable 
series of correlated characters, and that these combinations of characters are 
maintained when these types are bred with the sugar corns. Although je flint 
or starch character of the grains is not then visible, breeding tests show that one 
or the other of these is latent, so that there is a ‘‘flint” series of sugar corns and a 
“starch”? series. 
So far as evidence goes at the present time, the Mendelian method of behavior 
is most clearly present in crosses between the most nearly related forms, and 
shows the most decided tendency to break down in the crosses between more 
distantly related things. For this reason all studies of the behavior of species- 
hybrids become of the greatest importance. Hurst?* has made a survey of 
orchid hybrids with special reference to the inheritance of albinism, and finds the 
phenomena so similar to those already worked out in sweet peas and stocks that 
he is convinced that they present typical Mendelian segregation. Lock’? gives 
a report on some spccies crosses of the genus Nicotiana. This is only a prelimi- 
nary report and many points remain to be cleared up. He finds that the second 
generation of some of these crosses shows a wide range of distinct types, which he 
believes can be analyzed on the same basis as the sweet peas and stocks have been. 
Color of pollen and of corolla, and form of corolla tube (bulged or funnelform) 
showed typical segregation. In many characters pertaining to general habit, 
leaf form, etc., segregation was not present or only doubtfully. Lock suggests the 
possibility that “‘true-breeding” hybrids may result from the failure of any but 
homozygous combinations, this idea being made possible by the fact that very 
often the fertility of such hybrids is very low, so that but a small percentage of 
successful seeds is produced. This matter of non-splitting hybrids between 
species has also been presented by BuRBANK,?3 who points out that this presents 
a method of production of new species, probably more important than usually 
supposed. Although several of the instances mentioned by BuRBANK have 
not been sufficiently tested, there can be little doubt that the species-hybrids 
in Rubus present cases of this kind. Upon these exceptional situations the chiet 
attention of experimenters shou!d be concentrated. 
Another hopeful direction for research that is being taken up in several quarters 
is that of making analyses to determine the exact nature of the unit characters. 
Only in this way can we hope to discover the nature of the character-producing 
= ia E. M., A note on the inheritance in sweet corn. Science N.S. 29: 465-467. 
21 Hurst, C. C., Inheritance of ess in orchids. Gardeners’ Chronicle. Feb. 
6, 1909. 
22 Lock, R. H., A preliminary survey 
the Mendelian standpdint Ann. Roy. Bot. Gard. Peradeniya 4: 195-227. pls. 12. 
1909. 
*- the genus Nicotiana from 
23 BURBANK, L., Another mode of species-forming. Ann. Rep. Amer. Breeders’ 
Assoc. § : 4-41. 1909; also, Pop. Sci. Monthly 264-266. Sept. 1909. 
