4 INHERITANCE, FERTILITY, AND SEX IN PIGEONS. 



by law, of which Quetelet's curve takes no note. For the discovery of this law, 

 the history of the phenomenon must first be ascertained. It is from just this history 

 that the large-number curve diverts attention. 



But some will urge that this history is too complex and inaccessible to study. 

 Assuredly it is hopelessly involved in forms whose intcrminglings have gone on 

 for ages unrecorded. In many wild species, however, the record has run on with 

 such uniformity that the ancestry becomes practically a simple line stretching 

 back through thousands of years without a break. In such cases ancestry is all 

 summed up in parentage, and we can safely say that, knowing the species, we know 

 both parents and ancestors. In crossing two species we may predict the results 

 with considerable detail, for the hybrids do not carry a load of unknown latent 

 characters and the characters they develop can be referred directly to those of the 

 two ])arent species. 



In fact, in pure forms we see neither "sports" ^ nor "reversions," but straight 

 and full delivery of what heredity has packed in the germs. The delivery is as 

 precise as the blending of two parental germ-cells can make it. With such forms, 

 in which there has been not only continuity but purity of germ-plasm, we escape 

 endless perplexities, and Galton's problem of finding a precise numerical statement 

 for "the average share contributed to the personal features of the offspring by 

 each ancestor severally" becomes greatly simplified. 



In the case of a hybrid between the common ring-dove (Strcptopclia risoria) 

 and the very distinct Asiatic red ring-dove (Streptopelia hujiiilis) we do not have 

 to figure out the "shares" of parents, grandparents, etc. We see the characters 

 of both species so evenly blended in the hybrids and in the offspring of the h}d:)rids 

 when paired inter se that we can say that each parent has had an equal share, just 

 as we should describe the color of the mulatto as a "half-tint" and that of the 

 quadroon child of the mulatto and the white as a "quarter tint." The color, as a 

 whole and in each feather and part of a feather, the form and proportions, the size, 

 and even the instincts and the voice, the number of notes, manner, time, and rhythm 

 of delivery, follow closely the same simple formula. It is in such cases that we 

 see, as I believe, inheritance in its purest form, with "chance" phenomena retluced 

 to a minimum and the endless circuities of mixed filial relations excluded. 



The "conviction that inheritance is mainly particulate and much influenced 

 by chance" (Galton, Natural Inheritance, p. 19), and the conclusions that therefore 

 "the science of heredity is concerned with fraternities and large populations rather 

 than with individuals," sho\\s to what extremities we are pushed as the result of 

 attending too exclusively to forms of highly mixed ancestry. Nothing in the 

 experience of breeders is more certain than that long-continued, promiscuous inter- 

 mixing of stocks leads to instability and chaotic confusion in the transmission of 

 characters. Characters are thus, as it were, churned up until their typical distri- 

 bution in the developing organism is more or less deranged. Of course, chance 

 results are then conspicuous and laws are masked under distortions. Mixture is 

 random, characters are placed in unnatural relations, broken up, and scattered as 

 if sprinkled from a pepper-box. The appearance is very "particulate" and the 

 "large-number" curve is perhaps a refuge to be grateful for. Such conditions 



' A very few cases of "mutations" were later found. They are described in this vohimc and in Vohime I. — Editor. 



