SwANTON] INDIAKS OF THE SOUTHEASTERN UNITED STATES 799 



while the west meant weakness and death (Swanton, 1928, pp. 666- 

 670) . The little that we know regarding the medical practices of other 

 lower Mississippi tribes discloses nothing differing in any manner 

 from the corresponding customs of the Natchez. For a general study of 

 medicinal plants in this area, consult Lydia Averrill Taylor (1940). 



For Caddo medical practices, see Bureau of American Ethnology 

 Bulletin 132 (Swanton, 1942, pp. 219-226). 



CONCLUSION 



The material assembled in the present bulletin seems to support 

 the thesis that human culture in a natural physiographic area tends 

 to remain constant, or evolve at the same rate, that units of alien 

 population entering it tend to become absorbed by the culture they 

 find, while units separating from it tend to abandon much of the 

 culture they took with them. This is true when the cultures of the 

 peoples concerned do not vary too widely, and it does not mean 

 that culture is absolutely dependent on environment, or that past 

 history has no bearing on present condition. Diverse origins of units 

 in any natural area are marked by lags in the movement toward 

 conformity which are of different rates in different series of cultural 

 features. Upon the whole this lag is least pronounced in items 

 of material culture and such intangibles as are not clothed with 

 peculiar social or religious value, greater in factors of social and 

 ceremonial organization, still greater in linguistic differences, and 

 ordinarily greatest of all in physical characteristics. Where, as in 

 the Southeastern province, physical characteristics are not sufficiently 

 marked to be the occasion for emotional attitudes a steady mixture 

 of these features with all the rest is likely to take place so that 

 no accurate classification involving all of them is possible. Some 

 tribes may be placed definitely in one or another category but in cer- 

 tain cases it cannot be done. Language, on the other hand, gives us a 

 clear-cut categorization and is upon the whole the most useful single 

 criterion for this purpose. Our principal difficulty here is that there 

 has been a tendency to indicate linguistic stocks or families as if they 

 were all of equal weight and as if the differences between them were 

 equal, but, as has been shown by Professor Sapir and his pupils, 

 whether they are actually related or not, North American stocks may 

 be ranged in about half a dozen main structural groups and the stocks 

 themselves do not differ by equal increments. In the eastern part of 

 North America, for instance, the great Algonquian stock to the north 

 and east seems to diverge fundamentally from all the rest. A sec- 

 ondary distinction is to be drawn between the Caddoan and Iroquoian 

 peoples on one side and the Muskhogean-Siouans on the other, includ- 

 ing in the latter probably the other small stocks of the Southeast. 



