1896 | TOXIC EFFECT OF ACIDS AND SALTS UPON PLANTS 133 
comparatively firm experimental basis. The amount of dissocia- 
tion depends upon the strength of the solution. The more 
dilute the solution, the more complete is the dissociation, until 
at infinite dilution the dissociation is complete. When a certain 
acid, for example HCl, dissociates, the result is H-ions and Cl- 
ions; the H-ions are charged positively with electricity, while 
the Cl-ions are charged negatively, there being an equal number 
of positive and negative ions in order to preserve equilibrium. 
The manner of dissociation may be expressed by H* and Cl-. 
In the case of a salt, as CuSO,, for example, the dissociation 
will take place as *Cu* ions and ~SOj; ions, and in a similar man- 
ner for other salts, the radicle always being the electro-negative 
ton and the basic element or radicle the electro-positive ion. 
A comparison of the results obtained with the acids, with 
some investigations on the plant cell, is interesting as affording 
some light upon the nature of the effect produced by the acids. 
Klemm: states that ¥% to 1 pro mille HNO, causes the stream- 
ing motion of the protoplasm in the hairs of Zvianea to cease 
and also produces a granulation and aggregation of the proto- 
plasm. A 1 promille solution of HNO, would contain I gram 
of HNO, to 1o00% of water. The strength of solution which 
killed the roots of Pisum sativum was Nyy, which is equivalent 
to I gram of HNO, to 101,587 of water. For Zea Mais 
roots the killing point was the soy Solution, which is equivalent 
to I gram of HNO, to 25,396% of water. For the Cucurbita 
Pepo seedlings the roots were killed by the ,3,, solution, which 
's equivalent to 1 gram of HNO, to 50,793°% of water. From 
these figures it will be seen that the strength which was required 
to Produce a disorganization of the protoplasm in the 7rianea 
hairs was so much greater than that required to kill the roots of 
the Seedlings, that the toxic effect can hardly be due to a visible 
disorganization of the protoplasm. Klemm also states that the 
Same thing takes place with equally dilute solutions of H,SO, 
and HC], 
964 reno Banisationserscheinungen der Zelle: Jahrbiicher £. wiss. Botanik 28: 658- 
Ae 95. 
