THE NITROGENOUS PRINCIPLES OF URINE. 299 
The relative gain by growth, that o° No. 1 assumed as 
unity, is for No.1, — 1 
wow Be 6 
“OG 3, — 29 
6 ce 4, oe 298 
The crops were small, principally because the supply 
ofunitrogen was very limited. 
These experiments demonstrate that the substances 
added, in every case, aided growth by supplying nitro- 
gen. They do not, indced, prove that the organic fertil- 
izers entered as such into the crop without decomposition, 
but if urea escapes decomposition in a soil, as Cameron 
and Cloez have shown is true, it is not to be anticipated 
that the bodies employed in these trials should suffer al- 
teration to ammonia-salts or nitrates. 
Hampe afterwards experimented with urea and uric 
acid by the method of Water-Culture ( Vs. S¢., VII., 308; 
VIII, 225; IX., 49; and X.,175). He succeeded in pro- 
ducing, by help of urea, maize plants as large as those 
growing in garden soil, and fully confirmed Cameron’s 
conclusion regarding the assimilability of this substance. 
Hampe demonstrated that urea entered as-such into the 
plant. In fact, he separated it, in the pure state, from 
the stems and lcaves of the maize which had been pro- 
duced with its aid. 
Hampe’s experiments with uric acid in solution showed 
that this body supplied nitrogen without first assuming 
the form of ammonia-salts, but it suffered partially if not 
entirely a decomposition, the nature of which was not 
determined. Uric acid itself could not be found in the 
crop. 
Hampe’s results with hippuric acid were to the effect 
that this substance furnishes nitrogen without reversion 
to ammonia, but is resolved into other bodies, probably 
benzoic acid and. glycocoll, which are formed when hip- 
