1905] TRUE & OGLEVEE—TOXIC ACTION OF POISONS 5 
The first group of toxic agents tested were exclusively electrolytes, 
which at the very advanced degree of dilution here seen may be 
regarded as acting chiefly as ions. The possible presence of a resid- 
uum of molecules, especially in the case of HgCl,, is of no particular 
significance for the present discussion. Concentrations are always 
cited in terms of parts of a gram-molecule of the substance in question 
per liter of solution. 
Mercuric chlorid. 
Preliminary experiments were made to determine the toxic actiy- 
ity of the solution in the absence of insoluble substances. A concen- 
tration was then selected at which growth, although greatly depressed; 
is still possible before death results, and parallel cultures were then 
made in these concentrations both with and without the insoluble 
substance. The following table summarizes the results, growth made 
being indicated in millimeters: 
TABLE I. 
MERCURIC CHLORID. 
I gram-molecule Growth in 24 hrs. | Growth in 7o hrs. 
Mckee, PCS tao a eretresat ina ee Gaze 'n Se nace. GS es 2.0mm 6.5mm 
OC eeOe CAN ao Boia sis. Hela lean a wasted oa a gd 6.0 21.0 
oO, Rec eee ater nace sya ereree are due, mbeely ie non orice 10.0 28.5 
2G,000-F Crushed glaSS 24 shaw. care Sie wteeeiore toed oe 16.9 40.0 
Checkin waters: 24) newea cet cela ike. e acre 12.0 16.0 
It is clear that the presence of both sand and crushed glass here 
modifies very markedly the toxic influence of the mercuric chlorid. 
This amelioration is evident not only during the first twenty-four 
hours of the experiment, during which the roots were exposed to the 
corrosive sublimate solution, but also during the following period 
of nearly two days, during which the roots were placed in tap water. 
The course of the check experiment shows that the presence of the 
insoluble bodies exerts a clearly stimulating effect on the roots. The 
same may be seen in a less marked degree in the more dilute solution 
lacking the insoluble substance. 
Silver nitrate. 
The above methods were applied to silver nitrate in a large number 
of dilutions, with somewhat less marked results. 
