1896 | TOXIC EFFECT OF ACIDS AND SALTS UPON PLANTS 153 
11. CONCLUSION. 
1. In nearly all of the seedlings used quite a wide range in 
the sensibility to the same substance is to be noted. This is 
especially noticeable in the results obtained for the acids. In 
some of the salts, as silver salts and K,Fe(CN), and K,Fe 
(CN) ,, all three of the plants were killed by the same solution. 
2. Throughout the whole series of acids and salts used | 
have shown that the toxic action was due to the ions into which 
the substances split up in great dilutions. In some cases dis- 
sociation was not complete and the effect of the undissociated 
substance had to be taken into consideration. 
3. In all cases, except KCN, K,Fe(CN), and K,Fe(CN),, 
it was the electro-positive or cathion which produced the toxic 
action. In the three substances mentioned above it was the 
electro-negative or anions which produced the toxic action. 
4. In the cases investigated, compound ions, which contain 
elements that have a very high toxic action, lose their toxic 
action to some extent by being combined. This may take place 
where a comparatively harmless ion unites with one of high 
toxic value to form a compound ion, or where two ions of high 
toxic value are associated in a compound ion. 
The.theory of dissociation in dilute solutions has thus thrown 
light upon the physiological action of different substances, and 
the theory has itself been strengthened by these experiments 
upon living subjects. The results obtained by Kahlenberg and 
True have been confirmed throughout all of my experiments. 
I wish here to thank Dr. Kahlenberg for aid and many 
valuable suggestions, and for the kindly interest which he has 
taken in my work. _ 
In 
UNIVERSITY oF WISCONSIN, MADISON. 
