96 INHERITANCE, FERTILITY, AND SEX IN PICiEONS. 



"The points of weakness in the daughter (E) were shown especially in the obsolescent 

 bars, the right second bar being scarcely more than a shadow of a bar, and again in her 

 young age, being only about 7 months old. Her nest mate was a sister (also No. E), and 

 two females^ from a clutch show weakness in parents, and weakness in parents leads us to 

 expect it in the young. Furthermore, this dam was hatched November 15 from an egg 

 laid at the end of October — at a time of lowest energy in the parents." (XG 24, R IG) 



This pair of weak parents produced the following: 



A 1. (5 E-1) hatched 6/4/09; dead before 2/1/11; moderately chequered, black without white. 

 9 A 2. (5 E-2) hatched 6/4/09; dead on 10/15/09; whitened (see pi. 15). 



When 6 weeks old the second young (A 2 or 5 E — ^2) was examined, photographed 

 (pi. 15) and described. White color was in evidence; the two dark bars present 

 were invaded by white advancing from the feathers' tip. "This whitening of the 

 bars of the young was the result of parental weakness" (R 16). At the same time, 

 feathers were plucked to learn the color of a second plumage. 



"On October 15, 1909, 3 months after plucking, the bird has made but very little progress 

 in moulting. The plucked secondaries have been replaced, but still show white to about 

 the same extent as before. The outer primaries (5 or 6 of them) have not yet come out, 

 and apparently they are at a standstill. The right wing still remains intact and not more 

 than half a dozen juvenal feathers have been moulted. The bird seemed drooping or sick 

 for a week or two before death on the above-named date, but has had a good pen and good 

 care. I find that the tail feathers have been replaced and have come out with the original 

 amount, or very nearly, of the white. It turns out to be a female. The liver was some- 

 what blackened, and the intestine was swollen and full of watery contents. The early 

 death again testifies to physical weakness. The result — whitened bars and whitened tail 

 feathers in the offspring'' — is thus well accounted for without the aid of specific deter- 

 minants." (XG 24, R 16) 



The first mating of pure homers to be described involves a male homer (Hom. 1) 

 whose fertility had previously been tested with birds representing three different 

 genera, all of a different family from that to which the homer belongs. This male 

 had successfully produced young with two of these genera, and had failed to fer- 

 tilize eggs (4 tests) of the most modified or divergent* of these 3 — the crested 

 pigeon of Australia. After these tests of his fertility he was mated with a homer 

 (Hom. 3), and still later with his daughter. Varying degrees of fertility (reduced 

 in all) were shown in the family crosses with the various genera used — St. risariii 

 {M 2 and F 2), T. orientalis (2), Ocyphaps lophotes {Cp). When this bird was 

 paired with his own kind practically all eggs were fertilized; with his daughter 

 also he was fully fertile. 



This "fairly strongly" chequered and highly fertile male was mated with a 

 strongly chequered (dark) female to see if birds darker than either parent might be 



' The italics of tliis entire quotation (tliis and tlie two following quoted i)aragraplis) are those of the author 

 Almost everywhere, in the author's later manuscripts which deal with breeding, one finds a word or two on the 

 immediate particular factor or factors associated with a particular smnii nf weak germs. Probably nowhere better 

 than in these paragraphs has he written of a number of them at om i I jn i.n: 



* "Horwood (Nature, June 11, 1908, p. 126— Coloration of Hn.r~ i;--- nuics that, 'The intensUy of coloration 

 varies with age up to a certain point. Eggs of young birds are oftin un^pni i.d. Absence of markings is doubtless 

 due to deficiency of pigmentation. The last egg or eggs of a second brood, in fact, often lack normal coloration or 

 markings.' Age and health thus control the coloration, which is brilliant in a healthy but indistinct in an unhealthy 

 bird's egg." (R IG) 



' See Vol. I, table 2, etc. 



