162 Vererbung, Variation, Mutation. 



392) Selby, A. D. and Houser, True, Breeding Cigar Filier in Ohio. 

 In: Ohio*Agr. Ep. Sta. Bull. 239, S. 361—478, Apr. 1912. 



This bulletin reports the conditions surrounding tobacco improvement in 

 the Ohio tobacco filier district and records the results of the efforts of the 

 authors in producing new types of tobacco, both by selection and hybridization 

 of previously known varieties. The theory and practice of hybiidization and to- 

 bacco breeding are discussed somewhat in detail, together with the resulting 

 first generation fusion of characters and the second generation Variation. Hybri- 

 dization is the most potent known means of inducing Variation in tobacco. 



No matter how radical the hybridization, there resulted a uniform first ge- 

 neration of hybrid offspring, always more or less intermediate between the two 

 parents in general appearance and habit of growth, although certain features 

 are likely to be more like those of one parent than the other or in "Mendelian" 

 terms these features are "dominant". The first generation is nearly always more 

 vigorous and more productive than the average of its two parents, in many cases 

 exceeding the yield of the more productive parent. The explanation for this pro- 

 bably rests upon the fundamental relationship of the units of inheritance. It 

 seems probable that the units which have to do with yield are many and act 

 just as effectively when inherited from but one parent as when inherited from 

 both. This being the case if follows that if the poorer parent contains one or 

 more units which contribute" to yielding power not possessed by the other the 

 increase in yield due to these factors are simply added to that of the more pro- 

 ductive parent with the net result that the offspring surpasses even the more 

 productive parent. A certain percentage of plants in the second generation will 

 be found to breed true to type or very nearly so, but most of them will be 

 found to vary in some of their characters so that it usually takes several years 

 to establish a fixed type, depending somewhat upon the amount of difference in 

 the parent varieties and somewhat upon chance in selecting mother plants ho- 

 mozygous in their characters. While in theory it is possible to get all possible 

 combinations in the second generation of hybrids, yet in practice the enormous 

 number of plants required make it itnpracticable, and new types appear in the 

 third and fourth and even later generations. This does not necessarily mean 

 that new unit characters have been formed, but simply that new combinations 

 have taken place and that the immediate parents of these later "off-shoot" types 

 have been hybrid (heterozygous) with respect to some of their characters. 



The chief function of selection from established varieties is to maintain a 

 Standard of excellence already attained. The general methods of work together 

 with the results of the experiments are set forth in detail. Pearl. 



393) Lehmann, G., Bemerkungen zu Plantago novo, Völker. In: Monatshft. 

 f. d. naturw. Unterr. S. 143. 1915. 



Plantago nova Völker (vgl. Ref. Nr. 1287) ist keine neue Art, sondern lange 

 bekannte Monstrosität von PI. major. Sie schlägt um so eher nach PI. major zu- 

 rück, je magerer, trockener und fester der Boden ist, d. h. um so mehr er dem 

 gewöhnbchen Standort von PL major ähnelt. Loeser. 



394)Kearney, T.H., Mutation in Epyptian Cotton. In: Journ.Agr. Research, 

 Vol. II, No. 4, S. 287—303, July 1914. 



Egyptian cotton exhibits, although in a minor degree, the tendency to develop 

 new varieties by mutation which characterizes Oenothcra LamurcTciana. There is 

 a further parallel in the fact that in both cases very similar, if not identical, new 

 characters come into expression at different times and in different places. In. 



