1893.] PUBLIC DOCUMENT — No. 38. 233 



tion of one })art of permanganate of potash in two thousand 

 parts of water. Those of the other k)t received none of the 

 permanganate, but an equal quantity of water, and were, in 

 other respects, under identical conditions. In three weeks 

 a difference between the two lots was evident, and in a month 

 it had become very conspicuous. The foliage of the treated 

 l)lants was deeper green and much more abundant than that 

 of the others. Ultimately the plants which received no per- 

 manganate died completely, their leaves turning brown over 

 their entire surfaces, but showing no trace of the spot fun- 

 gus. The plants which received the permanganate remained 

 vigorous and healthy until taken out in the spring. 



In view of this experience, Mr. Philbrick was advised to 

 try the same treatment on a larger scale. This he did, and 

 reported, after an experiment extending through a large 

 part of February and March, 1892, that he could see abso- 

 lutely no difference between treated and untreated plants. 

 There is no reason for doubting and every reason for believ- 

 ing that this experiment was properly carried out, but its 

 results are puzzling, in view of our experience with a few 

 plants at Amherst. In the latter case the plants were in 

 excellent soil, and the result cannot be attributed wholly to 

 any possible fertilizing effect of the potash salt. It should be 

 said, too, that the plants which died had still an apparent 

 abundance of healthy roots, and their death did not appear 

 to be due to the few Nematodes which were present. This 

 view is sustained l)y the fact that plants died with the same 

 symptoms in the bench, which showed no trace of Nema- 

 todes or of any disease of the roots. It is, however, true 

 that the Nematodes in the roots of the treated plants disap- 

 peared, presumably as a result of the treatment, which has 

 been used with success as^ainst root-attackino; Nematodes. 



In view of all the above facts, it seems most logical to 

 conclude that, in the case of Mr. Phillu'ick's violets and in 

 the death of plants at Amherst, root Nematodes have little 

 or no share. We are left, then, to consider the only other 

 foreign organism observed in connection with the trouble, 

 the leaf-spot fungus. This, it may be said, has been believed 

 by Mr. Philbrick from the first to be the efiicient cause of 

 the disease. In April, 1892, a lot of plants, both healthy 



