438 Dandeno — Relation of Mass Action to Toxicity. 



nature. The question of fertilizers — one of the most impor- 

 tant to the farmer — is essentially a part of this question. For, 

 if the particles of soil can mechanically hold substances in solu- 

 tion, then there will always be a certain amount in the soil 

 which is not available to the roots of the plants. Moreover, 

 roots will be able to withstand a greater amount of poisonous 

 substance in the soil than they could if immersed in a liquid. 

 There are numerous suggestions which may arise along this 

 line, but the discussion in this paper is confined to two phases 

 of the aspect, — (1) that of the inhibitory effects produced by 

 pure sand upon toxic solutions, and (2) that of the relative 

 effects, in the same regard, of line and of coarse particles. 



Considerable has been done within the last eight or ten years 

 towards determining at what concentration of solution cer- 

 tain seedlings will survive, when the radicle is immersed in the 

 solution for a given period of time. Kahlenberg and True,* 

 1896, record a large number of experiments made with Lipinus 

 albus, and deduced certain results, some of which are quite 

 probably unwarranted. Their general method of preparing 

 solutions, a departure from the percentage method, is to be 

 commended, though some confusion in regard to naming of 

 solutions, and other errors of chemical formulas, make it neces- 

 sary to be cautious about accepting their results. Heald,f in 

 the same connection, worked with seedlings of Zea mais, 

 Pisum sativum and Oucurbita, but unfortunately confused 

 matters somewhat in the same manner, so that one cannot recon- 

 cile his table summarizing results, with the individual tables. 

 For example, on page 152, Heald gives the limit which for 

 corn, just allowed growth as 1/102400 eq., CuS0 4 ; while on 

 page 140, same paper, he records for the same seedling a 

 growth of 16*5 and 7 mm (for two successive days) in a solution 

 of CuS0 4 1/102400 mol. It seems a pity that more care was 

 not taken in this regard. Stevens J worked with spores of a 

 few fungi ; and Loew§ gave results of experiments made with 

 seedlings of indian corn. 



True and Gries|| worked with mixed solutions and this work 

 bears somewhat upon the line of thought followed through a 

 part of this paper. True^f recorded the results of a large num- 

 ber of experiments with Lupinus albus along a similar line to 

 that pursued by Kahlenberg and True. True and Hunkei** 

 used certain of the phenols in a similar connection. 



Moreover, the same problem has been touched upon from 

 another point of view. O. Loewff discussed the question of 



*Bot. Gaz., xxii, 1896. |[ Bull. Torr. Bot. Club, xxx, 390, 1903. 



-f-Bot. Gaz., xxii, 1896. U This Journal (4), ix, p. 184. 1900. 



JBot. Gaz., xxvi, 337, 1898. ** Bot. Cent., lxxvi, p. 9. 



§ Science, Sept. 4, 1903, p. 304. \\ IT. S. Dep. Ag., Bull. 18, 1899. 



