1 902 1 CURRENT LITER A TURE 385 



from most similar regions in that deciduous trees dominate instead of ever- 

 greens. The salt marshes with Spartina, Salicornia, and other characteristic 

 plants pass gradually into Typha swamps. Among the noteworthy ''adapta- 

 tions '* are sheaths which prevent the access of salt water, anchoring rhizomes, 

 and a number of well-known xerophytic structures. The beach flora is sparse, 

 and resembles the more northern beaches. Dunes are well developed and are 

 in some cases eighty feet high ; Ammophila is the character plant of the outer 

 dunes, but the more southern Uniola also has a place. The occurrence of 

 Saltx longifoHa, Cephalanthus, and Baccharis on the dunes is cited as an 

 evidence of the sand moisture ; perhaps they also indicate the advance of a 

 dune over a swamp. The occurrence of Acer rubrum and Nyssa sylvatica 

 on the lee dune slopes may have a similar explanation, as is the case on Cape 

 Cod, The abundance of Pinus Taeda with live oaks on the forested dunes 

 gives a southern aspect, though many of the character plants remain such far 



to the northward ; lianas are highly developed. The usual xerophytic 

 ** adaptations " are noted, though neither the soil nor air is dry. Thecharac- 

 ter of the drainage is the chief factor which determines the nature of the 

 inland vegetation, Pmus Taeda is the leading forest tree, though it is readily 

 followed by hardwoods in most places if removed. Abandoned fields are first 

 colonized by Andropogon virginictis, and later by pines. The leading decidu- 

 ous tree is Liquidambar, although oaks are abundant ; Fagus occurs in rich 

 soil. The swamps are of two types: (i) the dark or black gum swamp^ 

 which contains Acer rubrum and Taxodium as well ; (2) the light or "Juni- 

 per" swamp, in which Chamaecyparis rules, and in which there is less water, 

 though what occurs is more acid. This region is the northeastern terminus 

 of Merriam's Austroriparian ; many southern and a few northern plants 

 reach here their limits. The analysis of many important topics is keen, and 

 the paper is a highly welcome addition to ecological literature. 



C. C. Adams (Biol. Bull. 3: 115-13T. 1902) in a most valuable paper dis- 

 cusses the southeastern United States as a center of distribution. His data 

 are derived in the main from zoological material, but his conclusions are of 

 general interest. Among the criteria for determining a distribution center, 

 aside from fossil evidence, he gives the location of greatest differentiation, 

 of dominance or abundance, of maximum size, of productiveness, of con- 

 tinuity and convergence of lines of dispersal, of least dependence upon a 

 restricted habitat, of continuity and directness of variation along radiating 

 lines of dispersal. Using these and other criteria Adams shows the south- 

 eastern United States to be a great center of dispersal, at least for animals. 

 The chief highways have been the Atlantic coast, the Mississippi valley, the 

 Appalachian mountains. He makes a just plea for the dendritic as against 

 the zonal study of life ; lines of dispersal and divergence give a clue to many 

 of the great biological problems. This type of study is dynamic and genetic, 

 and thus has a great advantage over the more common methods. — Reference 

 has been previously made to the work of Kearney in the Appalachian 



