470 6- Vererbungslehre. 



is a pigmented area of the seed-coat which sometimes occurs around the 

 hilum. Some seeds are entirely white, others wholly colored, while there are 

 a number of types of „eye" between these two conditions. Certain of these 

 „eye" types are found to be heterozygotes between other types. At least 

 four types of eye are recognized, 1. small eye, 2. Holstein, 3. large eye 

 (heterozygote between the first two) and 4. Watson eye, and the results of a 

 series of crosses between these types and of tbese with „solid color", are 

 given. Four factor hypotheses, all of which are in harmony with the results 

 obtained, are the other. If, for instance, the red in difierent parts of the 

 rnaize plant is represented by independent factors, these must be strongly 

 bound together, for there is no „shuffling" of the these factors in F 2 , in 

 other words there is perfect genetic correlation between them. 



In certain other cases red cob color is allelomorphic to red (variegated) 

 pericarp color — a case of spurions allelomorphism (Bateson). Thus the 

 same characters were genetically correlated in certain cases and showed spu- 

 rious allelomorphism in others. Apparently, if the two dominant characters 

 are together in the same gamete in the beginning, they will show perfect 

 gametic coupling or genetic correlation, but if they enter the zygote from 

 separate gametes they remain separate and behave as allelomorphs. The writer 

 regards this as negative genetic correlation, the two dominant characters being 

 associated in the first case, and one dominant character being associated with 

 the absence of the other in the second case. 



It is pointed out that if these factors are definitely located in chromo- 

 somes, and if homologons parental chromosomes are separated in the reduction 

 divisions, we should have a mechanism to account for genetic correlation, 

 allelomorphism — spurious or otherwise — and independant inheritance. If 

 the representatives of two dominant characters were in separate chromosomes 

 of a gamete we would obtain the dihybrid ratio 9:3:3:1; if they were in 

 the same chromosome we should have perfect coupling, with the monohybrid 

 ratio 3:1 in F 2 ; if they were present in homologous chromosomes we should 

 have spurious allelomorphism and an F 2 ratio 1:2:1. 



The fact that crosses between tall and dwarf plants give in some cases, 

 in F 2 , the two parental types and in other cases a series of intermediates, is 

 held to indicate either that these are a number of separate proposed in ex- 

 planation. The inherited differences in the various types of seed-coat are 

 believed to be most probably due to differences in the functioning of certain 

 chromosomes, e. g., in the rate at which a particular chromosome manufac- 

 tures a particular enzyme under given conditions. Gates (St. Louis). 



1285) Morgan, T. H., The origin of five mutations in eye color in 

 Drosophila and their modes of inheritance. 



(Science N. S. 33,849. p. 534-536. 1911.) 

 Während eines Jahres traten in einer Fruchtfliegenkultur Tiere mit 

 weißen, blaßroten, dunkelroten, orangefarbenen und gefleckten Augen auf. Der 

 nicht kürzer als im Original zu fassende Bericht ist dort einzusehen. 



J. Schaxel (z. Z. Neapel). 



1286) Morgan, T. H., The origin of nine wing mutations in Droso- 

 phila. 



(Science N. S. 33,84S. p. 496—499. 1911.) 



Imagines, Puppen, Larven und Eier der Fruchtfliege Drosophila ampelo- 

 phila wurden Radiumstrahlen ausgesetzt. Eine der so gezogenen Fliegen wies 

 eine Flügelaberration auf. Mit ihren äußerlich normalen Geschwistern ge- 



