254 
Notes on two Species of Alternaria. 
By L. R. Jones anD A, J. GROUT, 
(Plate 308.) 
During the summer of 1896 we were engaged at the University 
of Vermont in the study of certain plant diseases, particularly 
the early blight of potatoes. The economic results of the work 
have beeri fully treated: by Professor Jones in the Ninth Annual 
Report of the Vermont Agricultural Experiment Station of 1895, 
issued in December, 1896. 
The present article aims to deal more fully with the taxonomic 
results of the work than was possible in the article cited above. 
Careful cultures, which were begun by Mr. C. C. Tracy the win- 
ter before, were carried on for several months and established be- 
yond a doubt that two entirely distinct species of A/¢ernaria were 
found on the cultivated potato; and a study of material from 
many different localities has also shown that these two species 
have not been distinguished by most students of the early blight, 
but have both passed under the name of Macrosporium Solani E. & 
M. Even Dr. Paul Sorauer (Zeitschrift fiir Pflanzen Krankheiten, 
6: Heft I.,) failed to distinguish the two species, although 
he made cultures from diseased leaves bearing both fungi, as is 
clearly indicated by his figures and the fact that both species 
were raised from potato leaves sent Professor Jones by Dr. 
Sorauer. 
The significance of this separation of the two species lies _ 
in the fact that one of the species is an active parasite causing the 
destructive early blight of the potato, while the other is in no way 
parasitic but a saprophyte growing on most decaying vegetable 
matter of every sort, being easily compared in this respect to the 
omnipresent Cladosporium herbarum. The true Macrosporium So- 
Jani E. & M.,is the parasitic species. It is very destructive to the 
leaves of the potato early in the season before Phytophthora i- 
festans begins to affect them. It forms peculiar “ target boards” . 
markings on the leaves as shown in this figure. 
In the central portions of these spots the characteristic spores 
may usually be found. We have seen whole fields with foliage so 
