92 
AMERICAN JOURNAL OF BOTANY 
[Vol. 9 
4. The species concept in the Fungi Imperfecti is of necessity a highly 
artificial one. The ultimate unit, an impracticable one for purposes of 
classification, is the pure line descended from a single spore. 
REFERENCES 
1. Stakman, E. C, and Levine, M. N. Effect of certain ecological factors on the morphol- 
ogy of the urediniospores of Puccinia graminis. Jour. Agr. Res. 16: 43-77. 1918. 
2. Rosenbaum, J. Studies of the genus Phytophthora. Jour. Agr. Res. 8: 233-276. 
1917. 
3. Burkill, I. H. The treatment to which the Para-rubber trees of the Botanic Gardens, 
Singapore, have been subjected. Gard. Bull. Straits Settlements i: 247-295. 
1915. 
4. Desmazieres, J. B. H. J. Notice sur quelques plantes Cryptogames nouvellement 
decouvertes en France, et qui vont paraitre, en nature, dans la collection publiee 
par I'auteur. Ann. Sci. Nat. Bot. II, 13: 181-190. 1840. 
5. Cooke, M. C. Some Indian fungi. Gre.villea 4: 114-118. 1876. 
6. . Cocoa-palm fungi. Grevillea 5: 101-103. 1877. 
7. . Blights on tea and cotton. Grevillea i: 90. 1872. 
8. Tanaka, T. New Japanese fungi, notes and translations. Mycologia 9: 167-172. 1917. 
