100 6. Vererbungslehre. 



chen wurden weißbauchig, ihre Bauchrandschildchen blaßblau statt, wie früher, 

 dunkelblau. Die erworbene weiße Bauchfärbung ist vererblich. In Kreuzungen 

 ergibt Rot mit Gelb kein Weiß, Weiß mit Weiß hingegen auch kein Rot 

 und Gelb, welche beiden Farben nunmehr in Form einer Scheckung auftreten. 



Temperaturerhöhung bewirkt beim Männchen der Zauneidechse, Lacerta 

 agilis, daß die zur Paarungszeit grünen, von brauner Rückenzobe abgehobenen 

 Flanken jahraus jahrein düsterfarbig erscheinen. Mäßige Temperaturerhöhung 

 bewirkt bei der Smaragdeidechse, L. viridis, daß das Weibchen eine lasurblaue 

 Kehle, gleich derjenigen des typischen Männchens bekommt, starke Temperatur- 

 erhöhung, daß beide Geschlechter dieser Form eine gelbe, der übrigen Unter- 

 seite konforme Kehlfärbung erhalten. Hitzekastration scheint auch bei L. agilis 

 und viridis, wo keine weitere Generation erzielt wurde, ebensowenig wie bei 

 den sich fortpflanzenden L. muralis und fiumana vorzukommen. 



Zwei Tabellen geben ziffermäßigen Aufschluß über die Zahl der verwen- 

 deten Versuchstiere, der Eier in jedem Gelege, der Daten ihrer Ablage usw. 



Autoreferat. 



253) CollillS, Gr. N., The value of first-generation hybrids in Com. 



(U. S. Dept. Agr., Bureau PI. Industry. Bull. 191. p. 45. 1910.) 

 The writer has made a series of crosses between primitive tropical types 

 of com and various varieties cultivated in the United States. The primitive 

 types (from China, Africa and the American Tropics) were also crossed inter se. 

 In 14 out of 16 such crosses there was an increased yield in the F l5 the 

 average increase being 53 °/ . It is believed that in corn as in other crops, 

 such as cotton, the „new-place effect", or the increased variability due to 

 slightly altered environmental conditions, will not operate upon F t hybrids. 

 The F x hybrids seed can therefore be produced and distributed from central 

 stations. 



The isolation of purely homozygous biotypes from ordinary varieties 

 decreases the yield, so that it remains to be determined whether Shull's 

 method of crossing pure biotypes is more advantageous than merely crossing 

 varieties which, owing to their partially heterozygous condition, already show 

 a greater yield than pure biotypes. Gates (St. Louis). 



254) Shull, Gr. H., Hybridization methods in corn breeding. 



(Americ. Breeders Mag. 1. p. 98—107. 1910.) 

 The author has previously suggested that the best method of breeding 

 Indian corn for yield is by crossing two pure biotypes each year and thus 

 utilizing the Stimulus from crossing which comes in the F t generation. The 

 present paper substantiates this point of view and shows that certain biotype 

 combinations furnish a larger yield in the F x than others, though reciprocal 

 crosses between biotypes give the same yield. The yield and the quality of 

 the crop produced are functions of the particular combination self-fertilized 

 parental types, and these qualities remain the some whenever the cross is 

 repeated. The production of the highest yield therefore „requires simply the 

 finding of the best combination of parents and then repeating this combination 

 year after year". Gates (St. Louis). 



255) SllOW, E. C. (University College London), On the Determination 

 of the chief Correlations between Collaterals in the case of a simple 

 Mendelian population mating at random. 



(Proceedings of Royal Society 83.B.561. p. 37—55. 1910.) 

 Mathematical. The author points out that measurement of a variety of 



