114 



SCIENCE. 



[N. S. Vol. XVI. No. 394. 



has also studied new systems of linear groups 

 in which the Galois field has been employed 

 al} initio. 



The aim of the present volume seems to be 

 to give a systematic presentation of these re- 

 sults, together with the necessary theorems 

 from the known parts of mathematics. Com- 

 paratively little knowledge is presupposed on 

 the part of the reader, but the generality of 

 the methods calls for considerable maturity 

 and training. It is to an unusual extent the 

 work of the author, and is a credit not only 

 to him, but also to all the mathematicians of 

 our country. We predict for it a place among 

 the few American works on mathematics 

 which are known and respected by the leading 

 mathematicians of the world. 



G. A. Miller. 



Stanford Ukiveksity, Cal. 



SCIENTIFIC JOURNALS AND ARTICLES. 



The Botanical Gazette for June contains the 

 following papers : Mr. A. Eimbach has re- 

 corded a series of physiological observations 

 on the subterranean organs of ten Californian 

 species of Liliacese. Although they are geo- 

 philous herbs of similar organization, they 

 show very different modes of self -burial. The 

 plants studied are grouped on the basis of these 

 methods. Mr. Ralph E. Smith has studied 

 ' The Parasitism of Botrytis cinerea,' and has 

 come to the conclusion that too much impor- 

 tance has been ascribed to a cellulose-dissolv- 

 ing enzyme. The two stages in the process 

 are a poisoning and a killing of the cells, and 

 their disintegration and utilization as food by 

 the fungus. The first effect seems to be pro- 

 duced by a substance, probably oxalic acid, 

 formed by the fungus as a by-product of its 

 metabolism. Following this a number of dif- 

 ferent enzymes are secreted that digest the 

 various constituents of the tissues. Mr. 

 Charles H. Shaw has published a study of 

 'The Development of Vegetation in the Mo- 

 rainal Depression in the Vicinity of Wood's 

 Hole.' In open pools anchored plants with 

 floating leaves are often confined to a zone 

 somewhat separated from the shore, their ap- 

 proach to the shore line being prevented by 

 the sweeping in of silt. The vegetation of the 



large open morainal pools, though undrained, 

 may be purely hydrophilous, but about the 

 time of the formation of the floating mat the 

 conditions appear to become xerophytic. The 

 marginal ditch which surrounds pond islands 

 and atolls is formed only in the woods, where a 

 dense felt of humus vegetation protects the 

 ground from erosion. Fallen leaves and other 

 organic materials swept from the forest tend 

 to smother the vegetation which might grow 

 there. In this way there is produced a belt of 

 open water surrounding an island, or ring of 

 vegetation. Mr. G. E. Webb has published 

 a ' Morphological Study of the Flower and 

 Embryo of SpircBa.' Some of the conclusions 

 are as follows : The order of floral development 

 is sepals, inner stamens,, carpels, outer sta- 

 mens, petals ; no archesporial cell or plate of 

 archesporial cells is differentiated in the 

 microsporangium ; the tapetum is cut off from 

 the outside of the archesporial mass; several 

 archesporial cells are differentiated in the 

 megasporangium. Mr. David G. Fairchild de- 

 scribes a precocious poplar branch observed in 

 Patras, Greece, and suggests the possibility of 

 using such precocity in the production of ear- 

 lier developing varieties of shade or fruit 

 trees. Mr. E. Mead Wilcox records observa- 

 tions on the numerical variation of the ray 

 flowers of Helianthus annuus. 



DISCUSSION AND CORRESPONDENCE. 



A METHOD OF FIXING THE TYPE IN CERTAIN 



GENERA. 



In view of certain recent discussions* as to 

 the proper means of fixing the types of genera 

 of early authors, when no type was specified, 

 we believe the differences of opinion arising 

 under existing codes of nomenclature will be 

 materially lessened by the adoption of the fol- 

 lowing rule: 



* See Cambridge, Ann. & Mag. Nat. Hist., 7th 

 Ser., VIII., pp. 403^14, November, 1901; ibid., 

 7th Ser., IX., pp. 5-20, January, 1902; Jordan, 

 Science, N. S., XIII., pp. 498-501, March 29, 

 1901 ; Allen, Bull. Am. Mus. Nat. Hist., XIV., pp. 

 325-334, November 12, 1901; Howell, Proc. Biol. 

 Soc. Wash., XV., pp. 1-9, February 18, 1902; 

 Allen, Proa. Biol. Soc. Wash., XV., pp. 59-66, 

 March 22, 1902; Cook, Sconce, N. S., XV., pp. 

 647-649. 



