138 



SCIENCE. 



[N. S. Vol. XXI. No. 526. 



by V. F. ]\Jarsters, and 'Evolution of some 

 Devonic Spirifers,' by A. AV. Grabau. 



The sessions of the succeeding days of 

 the general convention were given over to 

 the Geological Society of America. The 

 vice-president and chairman for section E 

 for the next annual meeting of the associa- 

 tion is Professor William North Rice, of 

 Wesleyan University, Middletown, Conn. 

 The secretary of the Philadelphia meeting 

 holds over, by constitution. 



Edmund Otis Hovey, 



Secretary. 



SECTION G— BOTANY. 

 During the recent meeting of this sec- 

 tion at Philadelphia, the following items 

 of business of public interest were trans- 

 acted. 



Professor C. R. Barnes, University of 

 Chicago, Professor F. C. Newcombe, Uni- 

 versity of Michigan, Dr. D. T. MacDougal, 

 New York Botanical Garden, Professor H. 

 M. Richards, Barnard College, and Dr. 

 Burton E. Livingston, University of Chi- 

 cago, were appointed a committee to con- 

 fer with a like committee from the Society 

 of Official Agricultural Chemists on the 

 meaning of the expression 'Plant Food.' 



The council of the association appointed 

 as delegates to the International Botanical 

 Congress, to be held at Vienna during the 

 coming summer. Professor C. R. Barnes, 

 University of Chicago, Mr. C. L. Shear, 

 U. S. Department of Agriculture, and Dr. 

 11. C. Cowles, University of Chicago. 



Dr. Erwin F. Smith, U. S. Department 

 of Agriculture, was elected vice-president 

 and chairman of this section for 1905. 



A joint session was held with the Myco- 

 logical Society on Friday afternoon. 



The following are the abstracts of papers 

 offered : 



Stages in the Development of Sium cicutce- 

 folium: George Harrison Shui.l. 

 There is great range of variation in the 



leaves of Sinm cicutafoliuut. the first 

 nepionic leaf being the most variable and 

 the bracts in the region of the umbel least 

 variable. The juvenile leaves and the 

 senescent leaves, which have been inter- 

 preted as atavistic, are shown to disagree 

 with each other in almost every particular. 

 The only cases in which the ancestry of a 

 species is definitely known indicate that 

 whatever change of structure gives rise to 

 new adult characters also results in 

 changed juvenile and senescent characters. 

 The relative simplicity of the juvenile and 

 senescent leaves is due to physiological 

 causes having no essential bearing on the 

 phylogeny of the species. Sium is meso- 

 phytic, hydrophytic and xerophytic at dif- 

 ferent periods of its development and these 

 structural differences are associated with, 

 but appear to be independent of. their 

 appropriate environmental conditions. 

 They are not a direct effect of the environ- 

 ment, but are due to the peculiar mechan- 

 ism of the protoplasm. Rejuvenescence is 

 the process by which protoplasm is changed 

 from the senescent to the juvenile condi- 

 tion. This may result through sexual re- 

 production or may be brought about in 

 other ways. In Sium it occurs regularly 

 in the lateral buds at the base of the stems 

 and may, under special conditions, occur in 

 any other vegetative bud or even in the 

 floAver buds. In passing from less complex 

 to more complex leaves the new characters 

 consist in incisions or indentations above 

 the base of the leaf, so that, in pinnate 

 leaves, the proximal pairs of leaflets are 

 homologous, and other pairs which are of 

 like order counted from the proximal pair 

 are likewise homologous. 

 Alternation of Generations in Animals, 



from the View-point of a Botanist: 



Charles J. Cuamberlin. 



This is an attempt to show that the egg 

 with its three polar bodies, and also the 

 primary spermatocyte with the four spores 



