486 SKINNER AND BEATTIE: EFFECT OF ASPARAGIN ON WHEAT 
The amount of phosphate stated as P.O; removed from the 
solutions during the experiment was 201.2 milligrams for the 
normal cultures and 326 milligrams for the cultures containing 
asparagin, a difference of 124.8 milligrams in favor of the asparagin 
cultures. 
The amount of potash stated as K,O removed from the solu- 
tions was 471.2 milligrams for the normal cultures and 485.6 
milligrams for the asparagin cultures. As with the phosphate the 
asparagin cultures removed slightly more potash than the normal 
cultures, 14.4 milligrams. 
The amount of nitrate removed during the course of the experi- 
ment was 437.2 milligrams by the normal and 305.4 milligrams 
for the asparagin cultures. The asparagin cultures, though 
making a larger growth, used 131.8 milligrams less nitrate. It 
seems that the plants absorb and use asparagin whether nitrate 
be present or not, the effect on growth being much more marked 
in the limiting case where no nitrate was present, and that in the 
other cases the compounds replaced the effect of nitrate. 
The culture work was throughout under strict chemical con- 
trol, so as to establish as definitely as possible that the effects om 
the plants noted were produced by the absorption of the compou 
as such. Nitrite, nitrate, and ammonia were tested for @ 
found to be absent, or, in the case of ammonia, present in traces 
only. Although neither nitrate, nitrite, nor ammonia was found, 
the plants, nevertheless, grew remarkably well, and the only 
conclusion justified by this experimental evidence is that a 
compound is directly absorbed and assimilated. With the strict 
chemical control exercised, all possibility of any extended actio® 
by bacterial or other external biological agencies seems exc oe 
If such effects were produced in these experiments, they ce ; 
only minor significance in the results obtained. Bacteria an 
$ 
; 2 . nd lant 
experiments on so large a scale, involving over 4 thousa he 
in a single test. Moreover, it may even appear question 
whether absolute sterility, as being too artificial a condition 0 ae 
determination of the effect of soil constituents 0M plants, W° 
be desirable. 
