194 ORTHOGENETIC EVOLUTION IN PIGEONS. 



The pigeons, wild and domestic, present a considerable number of specific char- 

 acters, the histories of which can be traced with exceptional fullness, sometimes in 

 great detail. In the wing-bars for example, where we have, not one such character 

 merely, but many, it is possible to read the several histories with much greater 

 fullness and certainty than would be the case if they occurred only in a single species. 



In the genesis of these bars it is possible to see that natural selection has not 

 been the primary factor, and that mutation, as defined by de Vries, has not been 

 required either as primary or secondary factor. It is only on Darwin's hypothesis, 

 that bars came first and chequers afterwards, that mutation would find a locus 

 standi. But origin de novo is an entirely inadmissible hypothesis when we can trace 

 the history of the bars back step by step to remote ancestral foundations. 



The steps are orthogenetic rather than amphigenetic; ecbatic rather than telic. A 

 definite goal is reached, but as a direct sequel of that step in the series which imme- 

 diately preceded it; not, I believe, as the result of activating an entirely new pangen 

 or set of pangens hitherto held in reserve, and liberated just in time and place to 

 unfold as independent units. 



The doctrine of germs laden with independent unit-characters, or pangens, each 

 predestined, so to speak, to flower in its own place and time, strikes me as teleo- 

 logical mythology, fine-spun to the verge of absurdity. We have not yet fathomed 

 primordial organization, but it is safe to assume that the germ sets out with a bio- 

 physical constitution of a given specific type, within which metabolic, generative, 

 and differentiating processes, under normal conditions, run on in a self-regulating 

 way. Developmental and regenerative regulation, as it becomes ever clearer, can 

 not, in my opinion, be reconciled with any scheme of pangen-regency. No determi- 

 nants preside over the building of a crystal, and yet there we have specific form and 

 symmetry in perfection. If we are to draw the line sharply between science and all 

 transcendental and telestic mysticism, we must regard the germ-organism as wholly 

 mundane in origin and nature. If the germ is a thing of evolution from purely 

 physical foundations — and any contrary assumption is a denial of the evolution 

 principle—then we may say that it is a self-builder within the limits of physical 

 conditions, and just as truly autonomic in its forms and behavior as is the crystal. 

 In the formation of a crystal self-determination is ever present, and so it must be 

 in the case of the organism. 



