January 26, 1906.] 



SCIENCE. 



143 



actually hereditary and which are not. If we 

 find that the dusky woodpeckers of Vancouver 

 Island retain this shade when reared in Arizona, 

 then humidity would be a real factor in the forma- 

 tion of species. If such hirds, transferred in the 

 egg to a region, should develop in the fashion 

 of the local race of this region, and not like their 

 own parents, theti the duskiness is not a true 

 specific or subspecific character/' The real char- 

 acter of the species would be found in the tend- 

 ency to develop dark plumage in humid surround- 

 ings and pale feathers under other conditions. 

 In such case humidity would he merely a factor 

 modifying individual development but not con- 

 nected loith the origin of species.' 



It is hard to believe, on reading the above 

 paragraph and the adjoining context, that the 

 writer has duly weighed the real conditions of 

 the problem; if such be the case, he must have 

 a concept of species and subspecies different 

 from that of most of those who have been 

 most intimately concerned with their consider- 

 ation. It is also hard to understand the mean- 

 ing of the term ' hereditary ' as used in the 

 above transcript. 



Young mammals in the nursling stage have 

 a pelage different in color and texture from 

 that later acquired; young birds have a char- 

 acteristic nestling plumage different in color 

 and texture from that of the adults, or from 

 that acquired with the first moult. Every 

 experienced mammalogist and ornithologist 

 knows that the local differentiation in color 

 between the subspecific forms of a given group 

 is often (but not always) much more strongly 

 expressed in the first pelage or plumage of the 

 young than in the adults of the same forms. 

 In view of such facts it seemingly goes with- 

 out saying that local differentiations are trans- 

 mitted from parent to young, and are heredi- 

 tary in the usual sense of that term ; doubtless, 

 no one questions their continued transmission 

 from generation to generation so long as the 

 environment remains stable. Probably also 

 few would question that were representatives 

 of a strongly marked local form (in the case 

 of birds, either as eggs or mature birds) to be 

 transplanted to a region markedly different 

 climatically from their natural home, they 

 would gradually lose their original character- 



' Not italicized in the original. 



isties and become, after a number of genera- 

 tions, more or less modified, in better agree- 

 ment with the new conditions of life. But it 

 would be apparently rash to expect a very 

 material change in a single generation. There 

 is apparently not the least probability that an 

 egg of a large dusky Vancouver woodpecker 

 taken to Arizona would hatch into a smaller 

 pale form like the race native to Arizona. 



The ease may be somewhat different with 

 fishes, which have a more lax organization, 

 are lower in vital energy, and are probably 

 much more plastic than birds ; yet it would be 

 of interest to know whether the eggs of the 

 Loch Leven trout, when taken to other waters, 

 hatch into trout like those that are native to 

 the waters to which the Loch Leven trout eggs 

 had been transferred. In the waters of the 

 Yosemite it appears to have been eight or ten 

 years after the introduction of the Loch Leven 

 trout before it was discovered that they had 

 become indistinguishable from the English 

 Salmo fario. It would further be of interest 

 to know whether, through' actual comparison 

 of specimens, it has been found that Salmo 

 levinensis, in losing its Loch Leven characters 

 in California waters, has not also acquired 

 ^ome slight differences from the true 8. fario; 

 for the California environment must be greatly 

 different from that of England. 



So far as known to me, no similar phe- 

 nomena have been observed in birds, through 

 their transference from one climatic area to 

 another. Diiring the last twenty-five years it 

 has been a common practise to restock certain 

 localities in southern New England and other 

 parts, of the northern tier of states with south- 

 em quail, in places where the northern birds 

 had nearly disappeared in consequence of 

 severe winters or other causes. It is even said 

 that pure northern stock is now hard to ob- 

 tain ; and I have heard ornithologists congratu- 

 late themselves that they had in their collec- 

 tions a few specimens of the original northern 

 bird, taken before the introduction of quail 

 from the south. It is also commonly believed, 

 by those who are in position to know, that the 

 quail of the northern states are now a mixed 

 race. As, however, the imported birds have 

 been brought from the middle portion of the 



