Analyses of Ashes of Plants, 



197 



how comes it that we can raise good crops of carrots without 

 inanure where, if turnips were planted, a failure must be in- 

 evitable? Carrots are constantly raised without manure, at all 

 periods of the rotation, and in all soils, provided they he deep 

 enough. This, we firmly believe, is the circumstance which will 

 afford an explanation of the readiness with which a crop of carrots 

 is obtained ; it is never meant that carrots will not be the better 

 for manure — on the contrary, no doubt a little assistance in 

 forming their leaves and roots will be invaluable to them ; but it 

 cannot be denied that common observation is in favour of the 

 position we now wish to make good, that carrots will grow to a 

 crop where beet and turnips will not. Several instances have 

 been given in the preceding pages of crops of 20 or 25 tons 

 grown without manure. Now, it cannot be thought that the 

 carrot has less need of vegetable food than other root- crops; nor 

 certainly must it be said that it does not need so much mineral 

 food as the beet or the turnip, since our analyses prove that it 

 does. The carrot requires as much food, both mineral and vege- 

 table, as either of these crops ; and the sole difference lies in its 

 powers of obtaining that food. We would hardly like to say that 

 it has more facilities for the collection of food from the atmosphere, 

 although its serrated leaves might justify such a belief; but it un- 

 deniably throws down its roots to a greater depth in search of 

 mineral nourishment — hence the supplies which enable it to 

 vegetate on a poor soil, provided only that the subsoil be good. 

 A stony subsoil is unsuitable to the carrot because of the mecha- 

 nical obstruction to its roots ; but in a good deep clay its long 

 taper roots have been traced to a depth of 10 feet or more, and 

 from this depth they convey to the surface all those mineral 

 riches which are indispensable to the growth of the plant which 

 collects, and beneficial and necessary to the crop which succeeds 

 it. The carrot, then, will yield a crop without manure ; not that 

 it does not require the rarest mineral food, but simply because it 

 has independent resources for the acquisition of that food. Is it 

 not, then, worth while to consider whether its cultivation is carried 

 to the extent that it might be ? Were it a crop not requiring mine- 

 ral nourishment, then its cultivation would be worse than useless, 

 for we have analogy with us for believing that the most valuable 

 food for animals is that which in its own growth has drawn most 

 largely on the resources of nature. It must be so, indeed, for in 

 the animal economy matter is only appropriated ('"'assimilated'* 

 is the term) ; it is never built up from its elements — in order, 

 therefore, that the complex principles of the animal frame should 

 be formed, the food must be complex; and so far as research 

 has yet gone, it is a rule which admits of no exception, that the 

 most highly complex and at the same time most eminently 

 nourishing vegetable substances (gluten, vegetable albumen.. 



