90 TWELFTH REPORT. 



attractions of solute and solution, whether it be in connection with 

 root or with leaf. An understanding of the mechanism of the plant cell 

 and of the relations existing between solute and solutions is necessary 

 to an appreciation of the situation. The older theories of osmosis are 

 inadequate to the exi)lanation of these phenomena as well as to those 

 relating to the production of nectaries. 



The importance of fungus excretions may be inferred by giving a 

 very prominent instance to illustrate it: Many of us have seen the 

 Fairy Ring mushroom growing in lawns or pastures. This fungus has 

 a peculiar effect upon the growth of grass associated with it. At this 

 (sjtring) time of the year, the grass on the lawn is likely to be twice 

 as long where the mushroom mycelium lies than it is elsewhere. The 

 color of the grass is of a deeper green and the ring becomes larger 

 (of greater diameter) year by year. A study of the matter reveals the 

 fact that the fungus excreta aids very materially in rendering available 

 the inorganic material — to be organized later — into plant food. This as- 

 sociation is decidedly favorable to the grass. 



The two chief conclusions developed out of the discussion here given 

 and of the experiments relative to it are: (1) Roots (of seedlings es- 

 pecially) excrete a liquid rich in orsanic matter, which is alkaline in 

 reaction at least for three or four days after excretion. (2) Leaves 

 excrete (generally in the form of dew) both organic and inorganic 

 matter, and also, to a certain extent, both organic and inorganic matters 

 are washed out of leaves by rain. 



East Lansing, Mich., Apr. 20, 1010. 



