Vererbung, Variation, Mutation. 321 



sult. Castle's conclusion that unit characters are modifiable is called in question 

 by East, who thinks a terminology of hypothetical units gives a simpler des- 

 cription of tlie facts. Gates (London). 



1026) Harris, J. A., A simple test of the goodness of fit of Mendelian 



ratios. In: Amer. Nat., Bd. 46, S. 741 — 745, 1912. 



Refers to the usefulness of a simple formula of Pearson for determining 

 the probable error of any series of Mendelian results. Gates (London). 



1027) Collins, G. N. (Washington), Gametic coupling as a cause of corre- 

 lations. In: Amer. Nat., Bd. 46, S. 569—590, 1912. 



This paper coutains a criticism of the general theory of "gametic coupling", 

 in which it has been assumed that the coupling must be according to such de- 

 finite ratios as 7:1, 15:1 or63:l, although there are no known facts to indicate 

 why these particular ratios rather than any others between them should occur. 

 Also the actual experimental results obtained would indicate couplings of cha- 

 racters in such ratios as 20 : 1 or 75 : 1 rather than those suggested, and without 

 very large numbers of individuals it is impossible to decide between such ratios 

 as 75 : 1 and 63 : 1, so that the latter ratio remains an assumption. 



Yule's coefficient of association is used as a criterion of comparison bet- 

 ween observed and expected results. 



The theory of gametic coupling has since been complicated by the fact 

 that the correlations are reversible, depending upon how they are combined in 

 the parents. New facts are presented regarding coherence or coupling of cha- 

 racters in Chinese and American maize. The general conclusion is reached, that 

 associations between characters, like the appearance of single characters, may 

 arise at different stages of ontogeny. Gates (London). 



1028) Emerson, R. A. (Nebraska), The unexpected occurrence of aleu- 

 rone colors in Fg of a cross between non-colored varieties of Maize. 

 In: Amer. Nat., Bd. 46, S. 612—615, 1912. 



A dwarf Tom Thumb pop com was crossed with a tall Missouri dent com, 

 iDoth having white seeds. Three generations of hybrid offspring were grown, 

 all having only white aleurone. The same Missouri dent x white-seeded Cali- 

 fornia pop corn also gave white seeds for three generations. Further, the two 

 (dwarf) pop corns were also crossed and gave white seeds in Fj, but the Fg ears 

 gave purple, red and white seeds in the ratio 75:21:530. This result is ex- 

 plained on a Mendelian basis as due to a tetrahybrid or a trihybrid cross. 



Gates (London). 



1029) Harris, J. A., A first study of the influence of the starvation 

 of the ascendants upon the characteristics of the descendants. IL 

 In: Amer. Nat., Bd. 46, S. 656—674, 1912. 



In this continuation paper the effect of starvation upon the descendants, as 

 regards number of ovules per pod, number of seeds per pod, and weight of seed, 

 is considered. The study is based upon three varieties of the bean, Phaseolus 

 vulgaris^ the ovules and seeds of about 130000 pods having been counted, and 

 over 110000 seeds weighed, the number of plants observed being 21000. It 

 is thought that even these numbers are rather small for the purposes of the ex- 

 periments. 



The following tentative conclusions are drawn: "Environmental conditions 

 which greatly reduce number of pods per plant, number of ovules formed per 



Zentralblatt f. Zoologie, allgem. u. experim. Biologie. Bd. 2. 21 



