UN) 
structures. The chief damage perhaps is done when the ears are 
attacked, although the presence of infected areas on other parts of 
the plant may have an influence on its vigor (Fig. 7). 
Maize smut differs from any of the others previously mentioned. 
The spores seem able to infect any young developing tissue instead 
of the young flower or seedling, as is the case in the other smuts. 
In consequence, from an initial infection on a young maize plant in 
the early summer we may have secondary infections on other 
plants throughout the season. The fungous mycelium does not 
become distributed throughout the plant. It occurs only locally 
and causes characteristic hypertrophy or enlargement of a local 
mass of cells. The infection takes place locally on the parts of 
the plant where the smutted growths ultimately appear. A period 
of only about two weeks is required for the fungus to complete its 
life cycle—for the spores to germinate, the germ tube to penetrate, 
the mycelium to develop and again form the spores. In this way 
a succession of smut pustules may appear in the plants during a 
single season. The spores appear to live over the winter in the 
barnyard or field. The entrance of the parasite into the host 
appears to a considerable extent to be dependent upon injury to 
the plant. Perhaps the explanation of the destructiveness of corn 
smut in the western corn belt of Kansas, Nebraska, and adjacent 
regions is due to the extensive injury tothe plants caused by the 
strong winds. 
The Earlier Investigations on Smuts—The smuts have been 
studied from various standpoints for very many years. ‘The ear- 
lier students were concerned with tracing out the nature of the 
disease and the life history of the causal organisms. Such investi- 
gations required painstaking efforts in order to determine accu- 
rately the significant facts in the life history of the parasite. Step 
by step investigators like Tillet, Prevost, Tulasne, Kuhn, Brefeld, 
Jensen, Maddox, and others brought out the essential points and 
established clearly the relationship between the parasite and its 
host. These investigators also were concerned with the relation- 
ship of the different species of smuts and their proper naming. 
The possibility of the control of the smuts has long engaged the 
attention of many investigators and all sorts of methods have been 
