MICHIGAN ACADEMY OF SCIENCE. 



307 



experimentation. The nature or origin of the lethal principle is as yet 

 unknown. 



In the realm of bacterial diseases of plants^ the work done has similarly 

 been confined to the enzymotic studies. Jones (1909), and Van Hall 

 (1903), have demonstrated the presence of lytic enzymes in liquid 

 culture media in which the bacteria lias been growing. There is little 

 or no contribution explaining the cause of the death of the cells. 



The series of experiments which follow were undertaken to determine 

 wliether the metabolic by-products produced by M. sarcinaeforme in the 

 culture medium, have any toxic eflfect upon the leaf tissue of red clover; 

 and, if such a toxic substance were present, to determine its nature. 

 Along with this, tests were made, using extracts from the fungus whose 

 by-products were studied. 



Concerning the technique involved, the author believes, that in at least 

 one respect, he is free from a criticism which applies to some con- 

 temporary work. In studying the toxic activities of various extracts 

 most of the experimentors have used sections of tissues or entire organs 

 detached from the living plant. While it seems extremely likely that 



Figure 15. Plant with van Tieghem rings. 



