G3 



From the table it will "be seen that the copper 

 salts are by far the most toxic of all the salts here stud- 

 led. These two salts are very closely similar in their ef- 

 fect on the germination of the spores, which is in accord 

 with the results of Clark ( loc. cit. ) and points al- 

 most conclusively to the commonly accepted idea that the 

 toxicity of such copper salts is mainly or entirely due to 

 the copper ion. The last mentioned writer found that the 

 concentration of copper salts which inhibited germination 

 were higher than those producing the same effect in this 

 investigation, a fact that may probably be due to differ- 

 ences in the organism he worked with; he found that his 

 five fungi varied markedly in their response to the same 

 stimulus. Also, Clark usually made use of nutrient media 

 while the present studies were carried out without its em- 

 ployment. It is quite possible that the presence of nutr- 

 ient substances might have modified the effect of the poi- 

 son. Duggar^^ found the nitrate of copper considerably 

 more toxic than the sulphate and also considerably more toxic 

 than it is here shown to be. In the work of Stevens^C^ the 

 two salts affected germination similarly and the concentrst- 



19. Duggar, B. I!., Physiological studies with reference to 

 the germination of certain fungus spores. Eot. Gaz. 31:38-65 

 1901. 



20. Stevens, F. i... The effect of aqueous solutions upon 

 fungus spores. Bot. Oaz. 26:377-406. 1898. 



