a 
296 HOW CROPS FEED. 
Glycocoll or Glycine* is a sweet substance that re- 
sults from the decomposition of hippuric acid under the 
influence of various agents. It is also a product of the 
action of acids on gelatine and horn. 
Guanine (C,H,N,O) + occurs to the extent of about 
"|, per cent in Peruvian guano, and is an ingredient of 
the liver and pancreas of animals, whence it passes into 
the excrement in case of birds and spiders. By oxidation 
it yields among other products urea and oxalic acid. 
Kreatin (C,H,N,O,) { is an organic base existing in 
very minute quantity in the flesh of animals, and occa- 
sionally found in urine. 
Cameron was the first, in 1857, to investigate the assimi- 
lability of urinary products by vegetation. His experi- 
ments (Chemistry of Agriculture, pp. 189-144) were. 
made with barley, which was sown in an artificial soil, 
destitute of nitrogen. Of four pots one remained without 
a supply of nitrogen, another was manured with sulphate 
of ammonia, and two received a solution of urea. The 
pot without nitrogen gave plants 8 inches high, but these 
developed no seeds. The pot with sulphate of ammonia 
gave plants 22 inches high, and 300 seeds. Those with 
urea gave respectively stalks of 26 and 29 inches height, 
and 252 and 270 seeds. The soil in neither case contained 
ammonia, the usual decomposition-product of urea. Dr. 
Cameron justly concluded that urea enters plants un- 
changed, is assimilated by them, and equals ammonia-salts 
as a means of supplying nitrogen to vegetation. 
The next studies in this direction were made by the au- 
thor in 1861 (Am. Jour. Science, XLL, 27). Experiments 
were conducted with uric acid, hippuric acid, and guanine. 
* Carbon...........+ 39.73 + Carbon............ 82.00 $Carbon.. ........ . 
Hydrogen... ...... 3.81 Hydrogen... .. 6.6% Hydrogen.. ee 
Nitrogen. -46.36 Nitrogen. 18.67 Nitrogen... . 
Oxygen...........- 0.60 Oxygen........ ..- 42.66 Oxygen. ..........24. 
