226 LOTSY AND KUIPER, A PRELIM. STATEMENT OF THE RESULTS OF MR. 
treads the hen at irregular intervals and not daily? Or, that, if 
he does so daily, only a few odd eggs are really fertilised? Is it a 
lack of fertility in the male? 
To the other points, the low percentage of fertile eggs to hatch out, 
and the early death of the two chicks born, which were quite healthy at 
birth and alittle later, we can not attach much importance, as in broo- 
ding so much depends on circumstances, f. i. whether the brooding hen 
sits well or leaves the eggs frequently, and on the right food given to the 
young birds, which in this case was broken paddy, canary seed, white 
ants and chopped onions. As it is known that even the adult lafayetts 
is a great ant eater, its chicks may very well be insect-eaters exclusively. 
Chopped onions, will certainly not be among their regular diet. 
Dr. Tuomas therefore concludes rightly, it seems to us, that „the 
results obtained give every indication that the complete fertility of the 
hybrids could be demonstrated if really favourable circumstances were 
obtained” 1). 
ANYHOW IT IS PROVED THAT F, HYBRIDS OF DOMESTIC FOWL AND 
LAFAYETTI ARE FERTILE ‚AT LEAST IN PART, AND SEGREGATE IN F,. 
Dr. THOMAS calls attention to the fact „that when domestic birds do 
revert, the direction of the reversion of the colour of the breasts of the 
males is always to red or brown and never to black. Even domestic 
black-breasted reds tend to revert to red or brown breasted ones. In 
this particular then, be it noted, the reversion is not to the G. bankiva 
pattern, which is black-breasted, but to G. lafayetti which has a reddish 
brown breast” 
We now know of course that , reversion”’ is a recombination of cha- 
racters present in the birds which interbreed, so that it depends pri- 
marily on the constitution of those birds what kind of „reversion’” will 
occur. As Dr. THOMAS is so positive in his statements in regard to 
reversion the senior author begged DR. Lowe of the South Kensington 
museum to examine the breast colour of the cocks of domestic fowl 
which had run feral on some island or other and ‚reverted’’ more or 
less to the type of bankiva, present in the glass case in the Hall of that 
1) It should however be noticed, that the results obtained point to a lessened 
fertility of the F, hens, as is shown by the difference in results obtained by pai- 
ring F, birds inter se and by backcrossing the F, cocks with the domestic parent. 
Thisis of some interest as HALDANE showed that in cases of lessened fertility after 
crossing it is the heterozygous sex (in poultry the female one) which suffers. 
