May 19, 1905.] 



SCIENCE. 



789 



of the minerals which are the sources of radio- 

 active substances, and by the spinthariscope. 



The research paper by Professor C. E. 

 Chambliss, ' Notes on the Rhinoceros Beetle,' 

 was read by title. 



The fifty-third regular meeting was held on 

 March 24, at 8 p.m. Professor S. W. Eeaves 

 presented a paper on ' The Problem of the 

 Duplication of the Cube.' Dr. F. H. H. Cal- 

 houn gave a report upon ' The Origin of the 

 Mont Pelee Mud Flow.' A careful examina- 

 tion of the dust comprising this flow showed 

 that it had been formed by the grinding of 

 crystal-bearing rocks at temperatures below 

 the melting point. Volcanic dust usually 

 consists of small isotropic glass particles with 

 or without a small per cent, of crystalline 

 material. The particles in the flow from 

 Mont Pelee were crystalline, broken, and some 

 of the quartz crystals showed the wavy ex- 

 tinction due to strain. This of course may 

 have been developed in the original rock mass 

 instead of at the time of the formation of the 

 dust itself. The following minerals were 

 recognized in the dust: quartz, feldspar, horn- 

 blende, mica, an opaque iron mineral, and a 

 pyroxene. The crystals were so shattered and 

 strained that accurate determination was im- 

 possible. 



Informal communications were presented on 

 ' the tantalum lamp,' ' life and work of Pro- 

 fessor A. S. Packard,' and ' the engineering- 

 problems involved in the raising of the Maine ' 

 by Professors W. M. Riggs, Haven Metcalf 

 and P. T. Brodie, respectively. 



Haven Metcalf, 



8ecreta7-y. 



DISCUSSION AND CORRESPONDENCE. 



SUGGESTIONS TOWARD A PHYTO-GEOGRAPHIC 

 NOMENCLATURE. 



The terms formation and association are, 

 perhaps, now used by most plant ecologists 

 and geographers with, something like scien- 

 tific exactness. The word formation suggests 

 the idea of an area of vegetation of a char- 

 acter marked enough to be essentially different 

 from contiguous areas, the prominent forms 

 of vegetation in this area having the same 

 general aspect and adaptations corresponding 



with distinct physiographic positions. Such, 

 formations do not show an even mixture of 

 plants, because such plants are collected into 

 definite groups, or societies dependent some- 

 what upon the general conditions of the en- 

 vironment, but more especially because of the 

 influence of historic or edaphic factors. Such 

 assemblages of plants are called properly 

 associations. The members of the association 

 are looked upon as vegetation forms. The 

 term fades is also a phytogeograpic concept, 

 happily used with scientific accuracy. But 

 the term zone is used somewhat loosely for 

 very different ideas. The word is used in a 

 latitudinal or climatic sense, and we speak of 

 temperate and tropic zones. It is used for the 

 areas at different elevations on the mountain 

 side, hillside or bluff face. Again it is used 

 to denote the arrangement of marine algse 

 on the sea coast, or for the concentric growth 

 of aquatic plants about the lagoon of a pond 

 or lake. 



Humboldt (1805) applied the word zone to 

 the vegetation, the distribution of which was 

 determined by latitude. Schouw (1823) fol- 

 lowed Humboldt and Bonpland in the use of 

 the word in the latitudinal sense, and Kabsch 

 (1855) also. It seems then that the word 

 should be used in the restricted sense of a 

 particular portion of the earth's surface de- 

 termined by referring its position to the 

 parallels of latitude. The concept of bands 

 of vegetation on the mountain side, hillside 

 or bluff face with respect to the altitudinal 

 distribution of plants is best preserved by the 

 use of the word helt, and we would si>eak of 

 forest belt, subalpine belt, alpine belt, and 

 where necessary this application could be ex- 

 tended to zonation on a bluff face. This 

 usage is suggested, notwithstanding the im- 

 portance of emphasizing the identity of zona- 

 tion due to climate and that due to altitude, 

 because for practical reasons the two ideas 

 must be kept distinct. The writer wishes to 

 suggest for the concentric bands of vegetation 

 at times so clearly marked in lakes or pond, 

 the term circumarea, for in mathematics, 

 circumarea is the area of a circumscribed 

 circle. We might then speak of a water-lily 

 circumarea, a cat-tail circumarea, a shrubby 



