G4 



tions required to prevent germination varied, with the dif- 

 ferent fungi used, from m/o4CC to m/20G. Many other invest- 

 igations of the effect of copper on the germination of fun- 

 gus spores have been carried out, with varying results. The 

 effect of this poison on algae has been studied by 

 Livingston, and Kahlenberg and True^^, Heald22, Jensen^^, 

 Szucs-^2^ and others, have investigated its toxicity toward 

 higher plants. The results obtained indicate that fungus 

 spores are considerably more resistant toward the toxic ef- 

 fects of copper than are either the algae or higher plants. 



In the order of their toxicity, Pb(NC2)2 follows 

 the copper salts, though not closely, with AlCKCj)^ next. 

 The effects of the last two salts on plants seems to have 

 been studied but little. Livingston employed them, however, 

 and found the same relation to hold true as is here brought 

 out. Also, Jensen finds that Pb(NC3)2 is somewhat less tox- 

 ic toward wheat seedlings than is Gu(N02)2. The nitrates 

 of zinc and nickel, which are next in the order of dimin- 

 ishing toxicity, are not exceedingly toxic toward the 

 spores of Gloeosporixaa . It is interesting to note that 



21. Kahlenberg, Louis, and True, Rodney H., On the toxic 

 action of dissolved salts and their electrolytic dissocia- 

 tion. Eot. Gaz. 22:81-124. 1896. 



22. Heald, F. D., the toxic effect of dilute solutions of 

 acids and salts upon plants. Bot. Gaz. 22:125-153. 1896. 



23. Jensen, G. H., Toxic limits and stimulation effects of 

 some salts and poisons on wheat. Bot. Gaa. 43:11-44. 1907. 



