Januaby 26, 1906.] 



SCIENCE. 



147 



by the systematist, or has rarely been consid- 

 ered at all, for he has no means of testing it, 

 and to him the two sets of adaptive characters 

 must be equally specific, whatever their origin. 

 Nor is it easy to see how a universal measure 

 of discrimination can ever be supplied, for 

 even if a few general laws were derived, as 

 doubtless they will be, from experimental ob- 

 servation of the kind suggested by Dr. Jordan, 

 it is not likely that they would be serviceable 

 in special cases much, if at all, beyond the 

 limits of what we now call local or climatic 

 variation, and, manifestly, it is out of the 

 question that every uncertain case can be 

 brought under such experimental conditions 

 as those which have shown the real relations 

 of the Loch Leven trout. Organic selection 

 has much emphasized this difference between 

 the logical and the practical ideas of species, 

 and has siipplied the taxonomist with a prob- 

 lem of which he has no solution in sight. It 

 seems probable that the lack of such a solution 

 is behind the most extreme of the opinions 

 held by the authors of the respective theories 

 of ' mutations ' and ' isolation.' 



Quite another modifying influence upon 

 present methods of classification appears in 

 the facts of analogous evolution, of which 

 paleontologists have been accumulating evi- 

 dence. If like environments tend to induce 

 similar modifications in unrelated groups, it 

 at once becomes evident that systems of classi- 

 fication based upon such likenesses of struc- 

 ture may not in all cases reflect the genetic 

 connection which, since Darwin, we have be- 

 lieved them to approach. Therefore, classifi- 

 cation in the modern sense being worthless if 

 it fails to correspond to descent, it seems not 

 unlikely that geographical considerations may 

 come to enter more largely into the composi- 

 tion of genera than has hitherto been the case 

 with conservative naturalists, for in a strictly 

 genetic system it would not be permissible to 

 place in the same genus species so widely 

 separated by present or past geographical bar- 

 riers that we are forced to believe that they 

 can not have developed- from the same source. 



Arthur Erwin Brown. 

 The Zoological Gardens, 

 Philadelphia. 



ETHNIC TYPES AND ISOLATION. 



Recently several articles have appeared 

 in this journal discussing geographical isola- 

 tion as a factor in the differentiation of spe- 

 cies, and the illustrative observations taken 

 from both the animal and plant life of North 

 America correspond in a way to well-known 

 ethnographical facts. The writer does not 

 intend to discuss the virtues of the isolation 

 theory as a condition of biological variation, 

 but wishes to call attention to the fact that 

 such a theory seems to account for a number 

 of differences in the culture of Indian tribes. 



It is customary to divide the aboriginal in- 

 habitants of North America into linguistic 

 stocks and it is estimated that there are at 

 least fifty distinct linguistic families north of 

 Mexico. These were distributed in a very 

 striking way. In the Mackenzie basin we 

 have the Athapascan stock, around the Great 

 Lakes, Hudson Bay and Labrador, down the 

 Ohio River and east to the Atlantic Ocean, 

 the great Algonquin group with an intrusive 

 Iroquois stock in the vicinity of New York 

 state. In the Gulf states were the Caddoan, 

 the Muskhogean, and a number of small 

 groups. The great plains and prairie area 

 was dominated by the Sioux and Shoshone 

 stocks. If in contrast to this we examine the 

 Pacific coast we find in California alone 

 twenty stocks and between the northern boun- 

 dary and Alaska ten other stocks. The Pueblo 

 region to the south presents conditions some- 

 what similar. Thus a brief resume of the 

 distribution of linguistic stocks in North 

 America brings to view relations strikingly 

 similar to the distribution of species as noted 

 by President Jordan. 



Some one has proposed to account for the 

 great number of Indian languages in Cali- 

 fornia by assuming that a few young children 

 lost now and then in the isolated valleys of 

 the country would, if they survived, develop 

 new languages. While ethnologists do not 

 take this theory seriously they often give ex- 

 pression to a similar view, viz., that a people 

 without a written language living for a long 

 time in a given area separated from the parent 

 stock will gradually form a new order of 

 speech. This is a theory of differentiation by 



