ü. Vererbungslehre. 533 



/ucht konstant ist. Die Überlegung zeigt, wie schwierig der sichere Nachweis 

 wirklicher Mutationen sein muß." M. Daiber (Zürich). 



1965) Morgan, J. H., Sex-limited Inheritance in Drosophila. 

 (Science, N. 8. 82,812. p. L20 122. 1910.) 

 A white-eyed male appeared in a peedigrec eulture of Drosophila. Thia 

 mutant bred t<> Ins red-eyed sisters gave F, all red-eyed, and F 2 red-eyed 

 5$, red-eyed rftf and white-eyed tftf. The white-eyed 'male crossed witb Ins 

 red eyed daughters (F,) gave red-eyed and white-eyed tfrf and $$ in appro- 

 xiniatdv equal numbers. The facts are aecounted for by supposing that all of 

 the spermatozoa of the white-eyed male contain a factor for white eyes (W) 

 and that one half of them contain a sex factor (X), white all of the'eggs of 

 the original red-eyed females carry a factor for red eyes (R) and a sex factor 

 (X). The white-eyed male is WWX and the red-eyed fem ale RRXX; the sper- 

 matozoa W and WX, and the eggs all RX. The hybrid males are RWX and 

 their spermatozoa RX and W. This hypothesis was verified by four different 

 sets of experiments: — 



1) white-eyed £x white-eyed q* 



2) red-eyed F 2 9 x white-eyed q* 



3) red-eyed Fj ^ x white-eyed tf 



4) white-eyed £ x red-eyed F t rf. 



When a white-eyed female was paired with a wild red-eyed male all of 

 the female offspring were red-eyed and all of the male offspring white-eyed, 

 showing that the wild males are heterozygous for red eyes as well as for sex, 

 white the wild females are homozygous for both. 



The conditions in Drosophila are exactly the opposite of those in Abraxas. 

 In Drosophila the mutant is a male and the wild male is heterozygous for 

 eye-color and sex, while in Abraxas the mutant is a female and the wild 

 female is heterozygous for color and sex. The author thinks it probable that 

 the mutant arose by the dropping out of the factor for red-eyes in a Single 

 egg, so that RX become OX = WX; this WX paired with a Spermatozoon W 

 gave WWX, a white-eyed male. The fertilization of such a mutated egg by 

 a Spermatozoon RX would give a heterozygous female which mated with any 

 wild red-eyed male should have * 4 white-eyed male offspring, but white-eyed 

 mutants have not appeared in such numbers as this ezplanation would require. 

 The experiments also show that the assumed coupling of R with X in the 

 spermatozoa of the male RWX is due to the fact that the R and X are com- 

 bined and have never existed apart. (Vgl. Ref. 1349.) 



N. M. Stevens (Bryn Mawr). 



13fiC>) Fultoil, K., F. Judsoll und W. NorriS, Congenital heart-block 

 oecurring in a tat her and two children, one an infant. 

 Amer. Journ. Med. Sc. 140,::. p. 339— 348. 5 Fig. 1910.) 

 Familiäres Vorkommen von Bradykardie. Es handelt sich nach den 

 Verff. um eine auricoventrikulare Inkoordination. Verff. nehmen als Erklärung 

 hierfür an, daß im anricoventrikulären Bündel eine kongenitale anato- 

 mische Anomalie bestehe. Lewin* (Berlin. 



1867) "Weinberg, W. (Stuttgart), Weitere Beitrüge zur Theorie der 

 Vererbung. 



(Arch. f. Bässen- a. (;• sellsch.-Biol. 7,2. p. i. 1910.) 



Weinberg untersucht in einer Fortsetzung seiner Beitrüge in Heft 1 

 dieses Jahrg. die biometrische Wirkung des komplizierten Polyhybridismus. 

 Er nimmt hierbei mit Davenport verschiedene Merkmale derselhen Reihe 



42* 



