Observations on Uebig's " Organic Chemistry ^^ 107 



with the best growers of double stocks, who first impoverish 

 and then enrich the plant. It would thus appear, that the quality 

 of the food can transform the one organ into the other, and that 

 they are convertible, not different ; the greater the quantity of 

 food, the lower in the scale of organisation is the product, as it 

 is necessarily more crude. P'ruit trees never bear well when the 

 vigour of their growth is excessive. 



He next continues to explain various actions that take place, 

 as the power of malt to form sugar from starch by the ferment- 

 ing principle ; and contends thence, that the power to effect 

 transformations does not belong to the vital principle, but is 

 purely chemical. The process, no doubt, takes place in another 

 form more complicated ; but he thinks it still possible to be dis- 

 covered. He speaks afterwards of the vital principle balancing 

 the chemical, and the excess of food to animals causing the 

 chemical force to predominate, and produce disease : in a 

 similar manner will the excess of food in plants produce disease, 

 though disease may arise, as in animals, from other causes. 

 After death, in plants, the chemical force prevails, and dissolu- 

 tion takes place, though more slowly than in animals. He 

 complains that the term vital principle is applied to every action 

 we do not understand, as the terms specific and dynamic in 

 medicine; and that we should not be deterred from examining 

 into actions by these names. It will, perhaps, be long before 

 we can give any other name than that of a principle we cannot 

 understand, to such actions as the transformation of leaf-bud 

 into flower-bud, or the formation of the leaf-bud, itself the rudi- 

 ments of a future branch. Will any chemical compound we 

 can produce generate these or any vegetable organ, with their 

 infinite modifications? And, though we could point out what 

 transformations are made, we might still be ignorant of the 

 power that produced them. While the blossoms are being 

 formed, he says, secretions are more abundant, and excretions, 

 also, of carbon and other matters. 



He next considers the fact, that distilled water and carbon 

 will not make a plant thrive well, and that rain water is neces- 

 sary ; the rain water containing a compound furnishing nitrogen, 

 one of the essentials of vegetable life, which, with hydrogen, 

 forms ammonia. 



On the Assimilal ion of Hydrogen, the next division of the 

 subject, he says, when hydrogen is fixed in the wood, the oxygen 

 set free is the same, whether we consider it to be produced by the 

 decomposition of the carbonic acid or water, but he thinks it most 

 probably the latter. The oxygen of the water being set free is 

 assimilated as oxygen, the oxygen of the carbonic acid returned 

 to the air ; which he estimates at the rate of 2,600 lbs. of oxygen 

 to be set free in the air from each acre of land (the weights and 



