No. 2, March, 1921] 



GENETICS 141 



foliage, fruit flavors, size of fruit, runners and sex. Pink flowers and doubleness were found 

 ta be dominant over white flowers and singleness. Because of its heterozj'gous condition 

 with regard to leaf shape Fragaria grandiflora is considered to be a hybrid of F. chiloensis 

 or chinensis and virginiana. Crosses of 9 X cT or 9 have thus far given 203 9 and 173 d" 

 or 9.—W. D. Valleau. 



929, RiCHEY, Frederick D. The inequality of reciprocal corn crosses. Jour. Amer. 

 Soc. Agron. 12:186-196. 1920.— Reciprocal crosses between varieties or strains of maize 

 are sometimes unequal. Possible causes of such inequalities are suggested as a difference 

 in the food materials furnished the young plants by the different maternal parents and a 

 difference in germinal reactions with different cytoplasms. The experiments show that 

 some type of sex-linked inheritance must at least be considered as a possible cause of inequality 

 between reciprocal maize crosses, by the unequal transmission from No. 199 as staminate and 

 as pistillate parent.— F. M. Scherti. 



'130. RiEBESELL, P. Einige zahlenkritische Bemerkungen zu den Mendelschen Regeln. 

 [Some remarks critical of ratios in Mendelian inheritance.] Biol. Zentralbl. 38 : 329-.340. 

 Aug., 1918.— An investigation of the criteria for goodness of fit of theoretical Mendelian 

 ratios to be observed. On any given hypothesis as to relation of hereditary factors to exter- 

 nal characters, number of factors may be found by mathematical process. Thus if one 



3" _ n, 

 character occurs only with presence of all factors, equation will be: ^„_^„ - ~ where to - 



number of factors, Ux and ni = observed frequencies of alternate characters, whence m = 



log n - log ni ^^^ ^ ^^ ^ ^^^^ ^^^ probability of two hypothetic ratios may be compared 

 log 4 —log 3 



in several ways: (1) by their deviation from the observed; (2) by the ratios of these devia- 

 tions to their standard deviation; (3) by the probabilities that the theoretical ratios shall 

 be found in a population in which the observed ratio has occurred; (4) by the ratio of the prob- 

 ability of the observed to that of the most probable value; (5) by the probability of a deviation 

 .ns great as or greater than that of the observed from the theoretical. For small numbers of 

 observations no one ratio can be picked out as the only likely one. All criteria depend on 

 assumption of Gaussian distribution, which is violated by hypothesis of linkage and other 

 extensions of Mendelian theory. Where more than one hypothesis is admitted by criteria, 

 ratios in F3 will often determine right hypothesis.— Jo^n Rice MiJier. 



931. Salaman, R. N. The technique of cross-fertilization in potatoes. Potato Mag. 3: 

 8, 12, 26. 1 fig. 1920.— Brief description is made of female and male organs of potato flowers 

 and difficulties encountered in cross-fertilizing are mentioned. Instruments and materials 

 required in crossing are given and the various operations of selecting buds, sterilizing, emas- 

 culating, labeling, covering, pollinating, protecting seed in field, harvesting and extracting 

 seed, sowing seed and growing seedlings are described in detail. A simple and less certain 

 method is also described as well as operations required in self-fertilizing. Successful fer- 

 tilizations are never more than 5 per cent of individual blossoms treated.— Richard Wellington. 



932. Salaman, R. N., and J. W. Lesley. Genetic studies in potatoes. The inheritance 

 of an abnormal haulm type. Jour. Genetics 10: 21-38. 4 pi. July, 1920.— Two distinct types 

 of potato stems were found and named respectively "prostrate" and "procumbent." The 

 former differed mainly from the normal in that the stems were either deficient or entirely 

 wanting in interfascicular secondary growth, consisting mostly of xylem, and in that upright 

 habit of growth was absent. The latter seemed to be an intermediate between "prostrate" 

 and "upright" varieties, as it resembled the "prostrate" in stem structure and the "upright" 

 in growth habit. In a study of the inheritance of the "prostrate" habit, it was found to be- 

 have as a recessive character, the ratios indicating that it differed from the "upright" in at 

 least two and probably three factors. No correlation was found between the "prostrate" 

 habit and other characters. — Richard Wellington. 



