534 6- Vererbungslehre. 



den Füßen soll ein „Gewächs" sein. Leider konnte Verf. diese Kranke nicht 

 untersuchen. In einem dritten Mißbildungsfall handelte es sich um eine exo- 

 gene Entstehung durch amniotische Abschnürung oder Druckwirkung; bei dem 

 25jährigen Manne fehlten an der linken, im allgemeinen sehr verkleinerten 

 Hand sämtliche fünf Finger; sie waren durch kleine, etwa 1 cm lange Fleisch- 

 wülste angedeutet, von denen der des Daumens etwas stärker ausgebildet war. 



P. Wagner (Leipzig). 



6. Vererbungslehre. 



(Siehe auch Nr. 1346, 1490, 1509, 1505, 1506, 1512, 1513.) 



1491) Bateson, W. and R. C. Pannelt, The Inheritance of the pe- 

 culiar pigmentation of the Silky Fowl. 



(Journal of Genetics 1,3. p. 185—203. 1911.) 

 The silky fowl is characterised by abundant black pigment in the meso- 

 dermal membranes. The Brown Leghorn lacks this pigment. When a Silky 

 male is mated with a Brown Leghorn female, the female chicks are fully 

 pigmented, the male chicks slightly; but in the converse cross chicks of both 

 sexes are slightly pigmented. In F 2 from chicks of the former mating, one 

 quarter of the chicks are fully pigmented, including males and females; F 2 

 from the second mating gives one eighth of the chicks fully pigmented, and 

 these are all females. In both eases chicks with no pigment, and with slight 

 or moderate pigmentation also occur. An F t male from either cross mated 

 with Brown Leghorn gives one quarter of fully pigmented chicks, and these 

 are all females, but Fj females mated with Brown Leghorn give no fully 

 pigmented young in either sex. These results are explained by the hypothesis 

 that 1. pigmentation is due to a Mendelian factor P, allelomorphic with its 

 absence, p; 2. that the Brown Leghorn possesses an inhibiting factor I, which 

 is absent in the Silky; 3. that the female is heterozygous for a sex-factor F, 

 which is absent in the male; and 4. that the factor I cannot be borne by a 

 gamete bearing F. From this it follows that the female Leghorn is hetero- 

 zygous for I, and has the Constitution Fflipp, and produces gametes Fip, 

 flp. On these assumptions the observed facts are explicable. The inter- 

 mediate grades of pigmentation are due to the fact that I does not completely 

 suppress the effects of P, so that successive grades of pigmentation are pro- 

 duced by the combinations PPii, PPIi, PPII, PpII etc. The hypothesis was 

 tested by mating pure Silkies and F, birds with a race lacking both P and 

 I (ppü), which gave the expected results. A small number of exceptions are 

 explicable on the assumption that an occasional FI gamete is formed by the 

 heterozygote Ffli. Doncaster (Cambridge). 



1492) Bonhote, J. L. and F. W. Smalley, On Colour and Colour- 

 pattern Inheritance in Pigeons. 



(Proc. Zool. Soc. 3. p. 601—619. 4 Plates. 1911.) 

 This paper describes experiments in colour-inheritance in domestic pigeons. 

 The characters concerned are 1. chequering, in which the feathers have a 

 light V-shaped patch at the distal end; 2. grizzling, in which the barbs of 

 individual feathers are partly white and partly coloured; 3. mealiness, in which 

 the feathers are like grizzled with white replaced by red; 4. blue colour, that 

 of the wild C. livia; 5. Silver, a very pale form of blue; 6. red. 



The results obtained are that qualitatively all the characters show Men- 

 delian inheritance, as follows: — Silver is dilute blue, and recessive to füll 



