30 
WALTER SPURGEON BEACH 
Conclusions 
1. The results of the present investigations indicate that certain species 
of Septoria are differentiated into biologic forms. 
2. Although some forms show a degree of adaptability in host relations, 
in general the species studied are limited to one or to a few closely related 
hosts which they can vigorously infect. 
3. In some cases the host range does not extend beyond the limits of a 
genus, while in other cases two or three related genera are included. 
4. In many cases the host ranges established by the experiments have 
been more narrow than the host indices indicate. 
5. Disease characters, as manifested by the host, vary with the host 
and with environmental conditions, and are therefore unreliable in taxonomy. 
6. Certain species of Septoria have been shown to vary considerably in 
morphological characters under different environmental conditions, and 
hence the value of measurements now given in specific descriptions is 
questionable. 
7. Inoculation experiments show that Septoria malvicola E. & M. and 
S. fairmani E. & E. are identical. 
8. Similar experiments show that the form of S. convolvuli Desm.. de- 
scribed upon Convolvulus arvensis is biologically as well as morphologically 
distinct from the type form of S. convolvuli described upon C. sepium, and 
is entitled to specific rank. 
The writer takes pleasure in making acknowledgment to Dr. F. L. 
Stevens, Professor of Plant Pathology, University of Illinois, for helpful 
suggestions and guidance in the preparation of this thesis. The writer 
also wishes to express his appreciation of the valuable assistance given by 
Prof. William Trelease, Head of the Department of Botany, University of 
Illinois, in the solution of questions of taxonomy. Thanks are due Fred 
J. Seaver, Curator at the New York Botanical Garden, and Vera K. Charles, 
Mycologist, U. S. Department of Agriculture, for furnishing data upon the 
host ranges of various species of Septoria. 
LITERATURE CITED 
1. Arthur, J. C. Cultures of Uredineae. Journ. Mycol. 11: 50-67. 1905. 
2. Carleton, M. A. Cereal rusts in the United States. U. S. Dept. Agr. Div. Veg. Phys. 
Path. Bull. 16. 1899. 
3. . Investigations of rusts. U. S. Dept. Agr. Bur. PI. Ind. Bull. 63. 1904. 
4. Cavara, J. liber einige parasitische Pilze auf dem Getreide. Zeitschr. Pflanzenkr. 
3: 16-26. 1893. 
5. Diedicke, H. Uber den Zusammenhang zwischen Pleospora und Helminthosporium- 
Arten. Centralbl. Bakt. Abt. 2. 9: 317-329. 1902. 
6. Desmazieres, J. B. Neuvieme notice sur quelques plantes cryptogames, la plupart 
inedites, recemment decouvertes en France, et qui vont paraitre en nature dans la 
collection publiee par I'auteur. Ann. Sci. Nat. Bot. II. 17: 91-118. 1842. 
7. Elliott, J. A. Taxonomic characters of the genera Alternaria and Macrosporium. 
Amer. Journ. Bot. 4: 439-476. 1917. 
