Dr. Hugo Mohly on Liehig's Organic Chemistry. 81 



times, plants must have existed before humus ; and so they do now 

 — witness the Lecanoras and Parmelias growing on the perpen- 

 dicular cliffs of granitic mountains. This reminds him of the ques- 

 tion, whether the egg or the hen existed first ; and being aware of 

 the abuse which has of late been made of scientific axioms being de- 

 rived from mere algebraic calculations, he says that all sorts of results 

 may be ex-calculated (herausrechnen) in that way. 



To settle the question about the existence of primeval humus, 

 Dr. Mohl makes the following remark on antediluvian vegetation. 

 " What do we know of the incipient vegetation of the primeval 

 world — and why, before the appearance of the highest developed 

 plants, such for instance as Ferns, should not others which can live 

 without humus, such as Mosses and Lichens, have prepared the hu- 

 mus necessary for the higher plants ?" This of course, is the eternal 

 progress of vegetation in all times and in every place of the globe. 



It is, therefore, clear (continues Dr. M.) that L. has completely 

 failed to prove that plants do not use humus for their food. Besides, 

 the question whether plants feed on organic or inorganic substances, 

 was mooted long before the publication of L's. work. Although it 

 is certain that the chief portion of plants is formed by the assimilation 

 of inorganic substances, yet, the collateral questions, whether they 

 receive organic as well as inorganic matter ; whether all or only some 

 plants require organic substances for their existence, — these questions 

 are far from an ultimate and scientifically- corroborated solution. 

 Conclusions, moreover, merely based on uncertain observations, or 

 made merely at random, cannot be of value, and ought to have been 

 replaced by minute and well-devised experiments. In this manner, 

 L. might have become eminently useful to science. He professes 

 (it is true,) to despise minute experiments ; nevertheless, the Appen- 

 dix to his Work contains the reprint of some made by Hartig, 

 which he adduced in corroboration of his doctrine. But it is un- 

 worthy of a great chemist (concludes Dr. M.) to mix up experiments 

 of men like Davy or Saussure, with those of a gentleman like 

 Hartig, who, we are sure, does not aim at the distinction to be con- 

 sidered a chemist, — a science foreign to his pursuits. 



The experiments which have been hitherto made relating to the 

 question of the organic or inorganic nourishment of plants, may be 



