IN THE VEGETABLE KINGDOM. 193 



this is a point which has been sufficiently proved by innumerable 

 experiments, conducted both on a large and a small scale. 



Now that we have acquainted ourselves with the different sub- 

 stances which contribute towards the nutrition of plants, and have 

 discovered that they consist of a few very simple combinations, 

 derived from inorganic nature, the question almost irresistibly 

 forces itself upon our notice, how the vegetable organism is able, 

 from these few substances, to generate such an endless diversity of 

 organic bodies ? But this, unfortunately, is a subject which admits 

 of little more than mere conjecture. In conformity with the prin- 

 ciples which we have adopted in this work of avoiding all diffuse 

 discussion of subjective views, and carefully abstaining from use- 

 less hypotheses, we can only permit ourselves to examine some 

 few of those conjectures, regarding the formation of organic matter 

 in the vegetable kingdom, which admit of being referred to defi- 

 nite experimental facts. The number of such facts, however, is 

 very small, notwithstanding the many laborious researches which 

 have been made in relation to this subject by some of our most 

 distinguished inquirers. Our general remarks on the study of the 

 vital processes hold good in a higher degree for the processes 

 connected with the formation of matter in the vegetable kingdom ; 

 for although we possess some few good isolated observations, we are 

 entirely deficient in quantitative determinations, without which we 

 can make no certain progress in our knowledge of the organic 

 world. We are even ignorant of the relation existing between the 

 carbonic acid which enters into the green parts of plants in solar 

 light and the oxygen which is simultaneously given off. Yet how 

 can we attempt to establish an hypothesis in reference to this 

 process, before we have in some measure determined the numerical 

 relations of the concurring substances ? Very few numerical 

 results have been obtained in phyto-chemistry, excepting some 

 scanty determinations of Saussure, from which it would seem 

 probable that about 2 parts of organic matter are formed in sun- 

 light for every 1 part of absorbed carbon. Were we even able, 

 chemically, to trace the qualitative and quantitative relations of 

 the different substances in the order in which they originate in 

 the plant, we should find that our very imperfect knowledge of the 

 molecular forces, which play so important a part in organic pro- 

 cesses, would prove very unfavourable to the comprehension of 

 the chemical history of the gradual development of organic matter 

 from such simple substances as carbonic acid, water, and ammonia. 

 Whilst, on the one hand, the great simplicity observable in the 



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