55 
OF GARDENING AS A SCIENCE. 
NO. III. 
The reading public have long been tutored in error by those who have been 
considered physiological authorities : this is a sweeping and somewhat bold assertion; 
but we are led to make it by the perusal of a work by a scientific German physician, 
which has recently appeared, and which promises to create a great sensation, perhaps 
an entire revolution, in the study of vegetable physiology ; we allude to " The 
Organic Chemistry " of Liebig. As an analytic chemist, the author ranks inferior 
to none ; and the views he takes of the chemical processes engaged in the nutrition 
of vegetables are so striking, that it becomes imperative to direct our attention to 
them in the course of these articles, in order to exhibit truths which heretofore have 
escaped the notice of the learned : we extract a few leading paragraphs now, ap- 
pending such comments as may be required to render more lucid the admirable views 
of the author. 
To understand the culture of a plant, the elements which constitute, or exist in 
its structure, must be known ; therefore, the first part of the work is " devoted to 
the examination of the matters which supply the nutriment of plants, and of the 
changes which these matters undergo in the living organism." Subject to the 
operation of the vital principle of a plant, which must never be lost sight of, it 
becomes an object of the greatest moment to determine what the organs of a vegetable, 
(that is, its tissue or structure,) and the fluids they contain, are composed of ; for if 
these be ascertained, the gardener is prepared to supply it with those substances 
which can be converted into nutritive aliment ; whereas, if he be ignorant of these 
leading points, he is just as likely (as indeed it constantly happens) to poison his 
plants, as to promote the healthy development of their structure ; for " the food 
which can serve for the production of all the organs of a plant must necessarily 
contain all its elements." We will number our quotations : — 
1st. " The substances which constitute the principal mass of every vegetable, 
are compounds of carbon, with oxygen and hydrogen in the proper relative propor- 
tions to form water. Woody fibre, starch, sugar, and gum, for example, are such 
compounds of carbon with the elements of water. In another class of substances 
containing carbon as an element, oxygen and hydrogen are again present, but the 
proportion of oxygen is greater than would be required for producing water by union 
with the hydrogen. The numerous organic acids met with in plants, belong, with 
few exceptions, to this class. A third class of vegetable compounds contain 
carbon and hydrogen, but no oxygen, or less of that element than would convert 
the hydrogen to water. These may be regarded as compounds of carbon with the 
elements of water and an excess of hydrogen. Such are the volatile and fixed oils, 
wax, and the resins. Many of them have acid characters. The juices of all 
