. Anai 



Explanation of Illusti 

 Index of Specific Xai 



PREFATORY NOTE 



The investigations, the results of which are set forth in this 

 paper, were begun in 1906 at Purdue University and have been 

 continued at the New York Botanical Garden, and at Columbia 

 University. To the officers and botanical staffs of these insti- 

 tutions the author would express his appreciation of the valuable 

 aid rendered. The writer has also enjoyed the freest access to 

 the private herbarium and library of Professor J. C. Arthur, of 

 Purdue University, and is under obligation to him for many valu- 

 able suggestions and much kindly assistance. 



In addition to the field studies made in the vicinities where the 

 work has been carried on, several important collecting and ob- 

 servational expeditions have been made to the Rocky Mountains, 

 one to the southeastern Atlantic states, one to the Mammoth Cave 

 region of Kentucky, and numerous ones to various localities in 

 Illinois, Wisconsin, and Michigan. 



The experimental studies of life-histories have been carried on 

 in the greenhouses of the Purdue University Agricultural Ex- 

 periment Station, during the growing seasons from 1906-1910 

 inclusive. These experiments form a part of an extended inves- 

 tigation of rusts conducted by the Station and the results have 

 been published in the annual reports of Cultures of Uredineae 

 (Arthur, 1907, '08 1 , '09, 'io 1 ), but are briefly reviewed here in 

 order to bring together the scattered information relating to 

 Gymno sporangium. 



In addition to the herbaria of the institutions mentioned above, 

 the writer has had access to the material in the Cryptogamic 

 Herbarium of Harvard University, Mycological Collection of 

 the U. S. Department of Agriculture, and the Arnold Arboretum. 

 The following institutions have loaned for examination either 

 a part or all of their specimens of the genus Gymno sporangium: 

 Iowa State College, Cornell University, Connecticut Agricultural 

 Experiment Station, Alabama Polytechnic Institute, West Vir- 

 ginia Experiment Station, Delaware College and Experiment 



