212 



SCIENCE 



[N. S. Vol. XXVII. No. 684 



or retard the succession. Succession under 

 natural conditions. 



The Influence of Wmd upon the Distribu- 

 tion of Plants in Iowa and Adjoining 

 Territory: B. Shimek. 

 Winds tend to produce xerophytic con- 

 ditions, and their effect in conjunction with 

 topography and drainage, upon the vegeta- 

 tion of the state of Iowa, is discussed. The 

 possibility of forest (mesophytic), as well 

 as xerophytic areas within the state is ex- 

 plained on this basis. 



Some Apple Leaf -spot Fungi: Carl P. 



Haetlet. 



The finding of eighteen apple leaf-spot 

 fungi in West Virginia is recorded, the 

 commonest ones being Coniothyrium pirina, 

 Coryneuin foliicolum, Sphceropsis malor- 

 um, and an undetermined species. The 

 two first named were grown artificially. 

 Inoculation work with both the Conio- 

 thyrium and the Coryneum indicated that 

 they were not capable of causing serious 

 leaf disease. Both fungi were found on 

 wood, the former apparently wintering on 

 dead twigs. 



On the Occurrence of Pith Spots in the 

 Wood of the Soft Maple: Hermann von 

 ScHRENK. (Read by title.) 



Observations on Change of Sex in Carica 

 papaya: M. J. Ioens. (Read by title.) 



Studies in the Genus Gymnosporangium: 



Frank D. Kern. 



This, paper gives a brief statement of the 

 problems encountered by those who began 

 the systematic study of the genus Gymno- 

 sporangium in this country, with an ab- 

 stract summary of the published results. 

 The data left by past workers was chaotic 

 and insufficient, but by selecting new diag- 

 nostic characters and by studying in detail 

 many specimens from all parts of the 

 United States the difficulties have been 

 overcome. For the purpose of bringing 



together the data in such a manner as to 

 be of material assistance in the determina- 

 tion of specimens, a key involving the char- 

 acters of the telia is presented. Notes are 

 given explanatory of changes in nomen- 

 clature, extensions of range, etc. It has 

 been found necessary to describe three new 

 forms. 



Vernal Aspect of the Chaparral Formation 

 of California: Pehr Olsson-Sefper. 

 (Read by title.) 



Periodicity in Spirogyra: W. F. Copeland. 

 The object of this paper is to mention 

 some results of investigation bearing upon 

 the seasonal or periodic activities of Spiro- 

 gyra. The work was continued for twenty- 

 two months in the laboratory and in the 

 field. Indoor work was in ordinary biolog- 

 ical laboratories, where over seven hundred 

 aquaria were used. Outdoor study was 

 limited to forty ponds within a distance of 

 twelve miles. At least thirteen species were 

 kept under observation. The period of 

 maximum abundance corresponded exactly 

 with the period of maximum conjugation. 

 The vegetative filaments disappeared at the 

 same time as the conjugating filaments. 

 When a species was in fruit out of doors, 

 it was also in fruit in the laboratory. Ex- 

 periments and observations seemed to indi- 

 cate that Spirogyra is not a perennial 

 plant; that its activities are limited to a 

 few weeks, or months at most ; and that the 

 vegetative and conjugating activities are 

 conditions resulting not so much from ex- 

 ternal as from internal environment. 



Types of Some Rocky Mountain Willows: 

 Caeleton R. Ball. (Read by title.) 



Dry Rot of Corn and its Causes: James T. 



Barrett. 



Diseases of ear corn which have been 

 called "dry rot" have been found, upon in- 

 vestigation, to be caused by several species 

 of fungi. The one which has been the most 



