Varietäten, Descendenz, Hybriden. 295 



the characters of O. ncbrmervis, 0. nanella, O. gigas, and O. lata 

 investigated in 1904 and 1905 from the same characters in O. lamarc- 

 kiana is given. In the comparisons of the means only 1 case out of 

 the 30 presented shows a difference between the mutant and the 

 parent species of less than the sum of the probable errors of the 

 determination of the two constants; in the other cases the deviations 

 ränge from 1.02 to 172.30 per cent, of the value found for O.lamarc- 

 kiana. There can be no question as to the significance of these results. 



Examination of the deviations in the variabilities shows that in 

 10 cases they are not greater than the sums of the probable errors 

 of the constants upon which they are based and hence may be left 

 out ot consideration. Of the remaining 20, 16 show a higher variabi- 

 lity in the mutant while only 4 show a greater variability in the 

 parent species. The results thus confirm the conclusion reached in 

 1905 that the mutants show a higher variability than the parent 

 species. It was then suggested that the variability of a character of 

 the mutant was dependent in some degree upon the magnitude of 

 its departure from the parent type; the results of the present investi- 

 gation are not in disagreement with this conclusion, but the evidence 

 in its favor from the present series of material is so slight as to be 

 insignificant. Hypotheses concerning the significance of these con- 

 ditions are suggested and discussed. 



Correlation coefificients are give for each of the seven series of 

 material. 



The results from these 63 calculations seem to negative the 

 View that the characters of the Oenothera mutants are generally 

 less highly correlated than those of the parent species; the question 

 is to be regarded as undecided with the bürden of the evidence in 

 favor of the view that there has been little change in correlation 

 associated with the establishment of new means and variabilities 

 by mutation, 



4. Pedigree Cultures of Other Species. 



Cultures of 0. biennis. Guarded seed of 0. hiennis yielded a 

 few atypic individuals. Upon self-fertilization, these gave only about 

 12 per cent. atypic plants; the remainder w^ere of the parent type. 

 Hybridization between the parental form and the aberrant form gave 

 the same results while the aberrant type when crossed with O. la- 

 ■marckiana and 0. rubrinervis gives an offspring in general similar 

 to that produced by typical 0. biennis. 



Cultures of O. cruciata. Individuais similar to those described 

 above were also found in the offspring of O. cruciata. 



Cultures of O. grandiflora. Cultures of guarded seed of O. gran- 

 dißora "Warrant the assertion that this species presents a complex 

 progeny analogous to that of lamarckiana, in which two well- 

 defined mutants are readily recognizable by reason of their striking 

 differences from the parent form". 



5. Hybridization of Oenotheras. 



O. cruciata X O. lamarckiana, While O. cruciata X <^- ln^narc- 

 kiana is monotypic and constant, the reciprocal, O. lamarckiana X 

 0. cruciata, "consists of three forms, one of which is indistinguishable 

 from the O. biennis cruciata which has been recieved from various 

 European gardens". 



O. lamarckiana X O. rubrinervis. This cross yielded: 0. lamarc- 

 kiana, 90; one of the mutants of O. lamarckiana, 1; O. rubrinervis, 

 221. Thus O. rubrinervis formed 71 per cent. of the entire culture. 



6) Inheritance of the Characters of Bud Sports. 



