142 LOTSY AND KUIPER, A PRELIM. STATEMENT OF THE RESULTS OF MR. 
bei Kreuzung hat sich kein grund dafiir ergeben, sie fiir inkonstant 
anzusehen. Aber nicht bloss nach die äusseren oder scheinbaren 
Vererbungsweise sondern auch nach ihren Anlagen- oder Faktoren- 
gehalte scheinen die verwendeten Rassetiere — wenigstens soweit 
die speziell herausgehobenen Eigenschaften, beziehungsweise Fak- 
toren Complexe in Betracht kommen — homozygotisch also auch 
faktoriell oder genotypisch rein zu sein”. 
Mr. Houwink, whose knowledge of practical poultry breeding 
and of the origin of poultry breeds is very extensive, was not at 
all convinced by this information and called in question specially 
the purity of the Partridge-Leghorns and the Buff Cochins. 
These breeds have a lot of dominant factors which can hide 
very much — 
We shall limit ourselves to the experiments discussed above, 
and not mention the „Ergänzungsversuchen” with other breeds, as 
the author himself cannot give us any guaranty with respect to the 
purity genotypical nor phaenotypical of this material. 
Generally the reciprocal hybrids in crosses of homozygous 
animals are identical apart from differences caused by sex-limited 
factors. The presence of other differences therefore suggests hetero- 
zy$osis of at least one of the breeds used. 
Besides, the reciprocal differences should be explained in another 
way than by heterozygosis of the P-material only if each Fy in 
males and females showed an absolute homogenity. 
Now what about v. TSCHERMAK’S reciprocal hybrids ? 
The cross Buff Cochin X White Minorca gave following results: 
Buff Cochin? X Minorca (old) white? Fy, 14 indiv. 6 only 



as pullets. 
Comb single broad broad, but lower and 
coarser than father. 
Feathers buff with tra- pure white yellow- buff with more 
ces of black or less green-black. 
; pullets black at first. 
Legs feathered, very clean legged average till strong 
heavy feathered. 
Legcolour | orange gray orange. 
One exception! With single comb, feathers foxbrown with partly 
greenish-black and some white; legs: clean, leg colour: yellow-brown. 
