a BOTANICAL GAZETTE [JANUARY 
cane sugar, and brought against one side of a row of penis 
the gelatin block on the opposite side was made up with we 
tilled water. Twelve seedlings of Lupinus albus were used ina 
temperature of 22°, and the duration of the experiment was 
twenty-four hours. All roots grew straight. et 
Since in the last experiment the roots had on each ie a 
gelatin solution of equal strength, it follows that on the side of 
the sugar solution there was an excess of osmotic pressure cofr- 
responding to more than 183.4°" of mercury. This, however, 
effected no bending. 
Another set of sixteen seedlings of Lupinus albus was set up 
between gelatin blocks, the one side having a 3.5 per roy solu- 
tion of cane sugar, and the other a 0.28 per cent. solution on the 
dry salt Na,HPO,. When the preparation was taken down 
twenty-five hours afterward, every root had grown into the 
_ sodium phosphate, the angles running from 30° to 75°. 
These two experiments certainly show that the curves toward | 
the sodium phosphate are not to be explained as osmotropism 
nor ascribed to any mere physical disturbance of the water con- 
tent of the cells. If the curves are due neither to injury nor to 
the osmotic action of the sodium salt (osmotropism or hydro- 
tropism), there remains probably but one explanation: We have 
here a true case of chemotropism of roots. 
Accepting the foregoing results as demonstrating the positive 
chemotropism of the roots of Lupinus albus toward sodium phos- 
phate, it would be interesting to know whether with strong 
solution of the same salt the root would show itself negatively 
chemotropic. 
A row of ten seedlings, having on one side a gelatin block 
made with distilled water, and on the other side a block made 
with 2 per cent. dry salt of di-sodic phosphate, had all their roots 
killed within a few hours. Another row of ten seedlings, simi- 
larly treated except that the gelatin on one side was made up 
with a 1.5 per cent. solution of the sodium salt, showed, after 
twenty-four hours, all the roots bent into the gelatin containing 
the chemical. All of the roots except one were dead. All had 
grown sufficiently, however, to make the curve before dying. 
