KUNKEL: SPORULATION IN MACROSPORIUM SOLANI my) | 
and upon the jimson-weed (Datura stramonium).” By growing the 
Macrosporiums obtained from these three hosts side by side in pure 
culture it is easy to observe that they are by no means alike. Not 
only are they different culturally, but the spores they produce are 
quite unlike morphologically. The spores of M. daturae have an 
attenuated beak that is very much longer than the beak on the spores 
of M. solani or M. tomato. The beak on the spores of M. tomato is 
finer than the beak on the spores of the other two species. The 
mycelium of M. tomato is also finer than the mycelium of the other 
two forms. The spores of M. daturae are larger and the spores of M. 
tomato are smaller than those of WM. solani. On such media as string- 
bean agar and glucose agar the three fungi show wide differences. 
M. solani produces a gray felty growth on string-bean-agar and 
usually colors it red. No such color is to be observed in the case of 
M. tomato and M. daturae on the same substratum. The growth of 
M. solani on glucose agar is a rusty gray color. Colonies of M. 
tomato and M. daturae on this same medium are blue in color. M. 
daturae on many different media produces colonies showing marked 
zonation, such as is not to be observed with the other two forms. 
These three parasites are unlike in so many different ways that the 
writer believes they should be considered separate species, rather 
than strains of a single species. It is, of course, probable that either 
fungus may infect more than one host. Sorauer (8) reports that he 
was able to infect tomato leaves with the Macrosporium from the 
potato. This does not prove, however, that the three hosts as they 
grow in nature are attacked by one and the same fungus. An examina- 
tion of the spores of the three fungi when grown side by side in wounded 
cultures brings evidence that this is not the case. 
The method of obtaining abundant sporulation in cultures of M. 
solani here described makes possible more extended infection-experi- 
ments than have hitherto been undertaken. It is believed that it 
will also be of service in any study of the systematic relationships of 
the genus Macrosporium. The principle involved in the response of 
the early blight fungus to a wound-stimulus is one well known to 
science. Conditions unfavorable to vegetative growth often lead to 
fruiting in unprolific plants. The orchardist recognizes this truth when 
he prunes his trees or feeds them with fertilizers poor in nitrogen 
compounds. 
BIBLIOGRAPHY 
1. Duggar, B. M. Fungous Diseases of Plants. Ginn and Co., New York, 1909. 
2. Eries, H. (Syst. Myc: 32373. 1829. 
3. Galloway, B. T. The Macrosporium Potato Disease. Agric. Science 7: 370- 
382. 18093. 
