36 DR. SCHLEIDEN'S THEOEY OF AGIUCULTUHE. 



In the middle of Russia the corn which supplies the market 

 of Odessa is produced year after year on the same ground without 

 any manure. The straw is simply burnt. Sometimes indeed the 

 produce is only six or seven fold, but occasionally very rich. 

 The stems of the wheat are frequently as thick and tall as reeds, 

 and the leaves like those of Indian corn. 



In some parts of Malaga wheat and barley are grown alter- 

 nately without either dung or fallow. In Arabia Felix raw 

 manure is replaced by water or burnt camels' dung. 



In Hindostan the ground yields two harvests without manure, 

 the first principally of vetches, the latter of Indian Corn exclu- 

 sively. In the rice districts, comprising a great part of Asia, 

 organic manure is not applied. The Chinese however lay great 

 stress on vegetable ashes, and collect the weeds for burning. 



In Van Diemen's Land fifteen successive crops of wheat are 

 taken without manure ; the land is then suffered to run wild, 

 and when covered with Acacia scrub the trees are burnt, and the 

 soil is again fit for cultivation. The same is the case at the Cape 

 of Good Hope, and many like instances might be produced. 



As examples of plants which yield a great produce without 

 organic manure, we may mention Indian Corn, Rice, Sugar-cane, 

 Coffee, Cacao, Banana and Plantain, Manioc and Yam, Cotton, 

 Indigo, and a great portion of Tobacco. In fact the 200 or 

 600 fold produce of Indian Corn in Mexico without any manure, 

 puts to shame our 12 or 15 fold harvest with every effort of 

 agricultural skill. 



The following considerations show clearly tiiat in no case do 

 the organic substances contained in the ground perform any direct 

 part in the nutrition of plants. Humus, taken in its widest 

 sense, is nothing more than the undecomposed parts of animal 

 and vegetable substances. Before organic beings appeared on 

 our earth, there could have been no organic mould ; but even 

 supposing such to have been the case, and in whatsoever degree, 

 the earth must long since have been a wilderness had plants lived 

 on organic matter. The organic substances which an animal 

 devours are, to the extent of at least a half, entirely con- 

 sumed by the process of nutrition ; and the more or less rapid 

 combustion of decomposition wherever life has ceased, raises the 

 amount of complete destruction of organic matter to something 

 quite enormous. The process of destruction may be estimated 

 as follows : — For every rod of ground (containing 100 square 

 feet) we may reckon at least 200 lbs. of destructible organic 

 matter, of which 4 lbs., according to De Saussure's direct ex- 

 periment, are changed into Mater and carbonic acid. Taking 

 the surface of productive land in the whole earth, we have 3 

 millions of square miles, and thus 104 billions of pounds are annu- 



