HOUWINK S EXPER. CONC. THE ORIGIN OF SOME DOMESTIC ANIMALS 251 
have possessed the silverfactor, notwithstanding the fact that both are 
black red. 
Now let us consider the other F; animals. 
The hen 573.1, the only one raised from the 573 experiment, was born 
May 25 1920, sent to Mook Dec. 1921 and in the spring of 1923 to the 
senior author, where she still is. 
She is an almost exact replica of her silvery mother, but golden, 
while the mother is silver. 
This is, as it should be, because a silver hen is always Ss and a gold 
cock (the father 276.11) is — if we abstract from the possible presence 
of the inhibitor factor I — always so. 
We therefore get: 
silver hen 276.12 gold 4 a 11 
a Ns 
Les 
FM ss MM Ss 
gold hen silvercock, heterozygous for S 
The same black red cock 276.11 gave with the silvery hen 276.13, the 
sister of the one used in the former cross, 4 chicks: 574.1 ; 574.2; 574.3; 
574.4 born on April 6 1920, all of which died immediately after birth. 
The junior author noted down at the time: , Two of these chicks were 
brown with a black dorsal stripe, one was a little lighter, one almost 
white with a small dark spot on the back.” 
Of the chicks to be expected from such a mating Punnett I. c. p. 66 
says: 
„A silver grey hen mated with a black red cock will give chicks of two 
types in down color viz. ordinary brown striped chicks and the silvery- 
blurred brown-striped a form characteristic of the Duckwing.type. The 
former will be the pullets, the latter the cockerels.” 
Probably therefore the „lighter brown” chick was a silvery blurred 
striped one e. g. a duckwing cockerel, the two brown striped ones gol- 
den pullets and the nearly white one a pale colored or wheaten colored 
segregate from the bankantams, similar to the ones we got from the in- 
breeding of these. 
Let us now look at the F3 descendants of the other Sonnerati-cock. 
Their genealogy runs thus: 
