506 ORGANOLOGY. 



the functions of the lungs. If, also, we may assume with Mulder, that 

 a part of the oxygen which is thrown off by the leaves results from the 

 change of starch into wax, then this proposition sinks into comparative 

 insignificance. We may calculate roughly how much oxygen is thus set 

 free. An acre of clover yields in a year, according to Boussingault, 

 2,153-5 Ibs. of clover, which contains : 



1020-68 Ibs. carbon. 

 107-70 hydrogen. 

 8 14 -04 oxygen. 

 45-21 nitrogen. 



If we suppose that all the nitrogen was derived from ammonia, and 

 all the carbon from the carbonic acid, we should arrive at the following 

 results : 



1,020-68 C +2,670-74 O= carbonic acid. 

 45-21 N + 9-26 H=ammonia. 



107-70 H + 9-56 H + 786'00 0=water. 



814-44 O - 7,8600 O = 28"040. 

 2,670-74 21-04=2642-7 O, which must be excreted. 



But, according to Mulder, 10 eq. of starch = 20,420-0, exactly 3 eq. of 

 wax ( = 13,070-2) + 3,153-0 water + 4,197'0 oxygen, or the excretion of 

 2,642-70 Ibs., agrees to the formation of 8,229-8 Ibs. of wax, and the de- 

 composition of 12,762*3 of starch. But 21.53-5 Ibs. of dried clover could 

 not possibly contain 8,229*8 Ibs. of wax. It would afford, when extracted 

 by ether, about 86' 14 Ibs. of fatty matters. The excretion, then, of 

 oxygen, in consequence of the change of starch into wax, agrees with 

 about a hundredth part of the collective process. 



But take whatever view we will of the nutrition of plants, it remains 

 certain that a skilfully cultivated soil never becomes poorer in organic 

 compounds containing carbon, but even richer ; thus proving, setting 

 aside the loss of carbon from the soil by decomposition, that the greater 

 quantity of carbon in the harvest is not derived from the manure, but 

 from carbonic acid. An acre of land, in good culture, yields 790-8 Ibs. 

 of carbon more in the harvest than is contained in the manure ; to fix this 

 quantity of carbon not less than 2,000 Ibs. of oxygen would be set free, 

 which, according to Mulder's hypothesis, would represent the formation 

 of 6,300 Ibs. of wax. 



On such necessities hangs the doctrine of the nutrition of plants, in 

 order to account for the excretion of 2,000 Ibs. of oxygen, we are re- 

 ferred to a process which will not yield more than 30 Ibs., and the pre- 

 sence of 2 Ibs. of sulphur is derived from 400 Ibs. of gypsum, employed 

 in the culture of the plants, and which contain 90 Ibs. of sulphur. Of 

 the botanists and agriculturalists who derive the carbon of plants from 

 humus and manure, the former have forgotten their own experiments, the 

 latter never knew them. The tables of Boussingault were not required, 

 as every German manual of agriculture contains calculations of the 

 quantities of manures and harvests which, if the elementary substances 

 had been properly calculated, would have afforded results that would 

 long since have pointed out the true laws of nature. All who have 

 written upon this subject have failed to take a general view, and on this 

 account all earlier works, some few of the oldest excepted, are utterly 

 useless. Whoever writes on these matters ought to give new and exact 

 researches, in order to save himself and others from error. 



