250 
GARDENING AS A SCIENCE. 
subjects of investigation ; but tliey forget that the knife of the anatomist must 
dismember the body, and destroy its organs, if an account is to be given of their 
form, structure, and functions. 
u The second cause of the incredulity with which physiologists view the theory 
of the nutrition of plants by the carbonic acid of the atmosphere is, that the art of 
experimenting is not known in physiology, it being an art which can be learned 
accurately only in the chemical laboratory. Nature speaks to us in a peculiar 
language — in the language of phenomena; she answers at all times the questions 
which are put to her, and such questions are experiments. An experiment is the 
expression of a thought : we are near the truth when the phenomenon elicited by 
the experiment corresponds to the thought ; while the opposite result shows that 
the question was falsely stated, and that the conception was erroneous/' 
This is perfectly true, and beautifully expressed ; but where is the attack ? 
We find it on the other side, in the decided hostility which has marked the 
reviews of Liebig's work, and wherein a spirit of rancour, of asperity, and sarcastic 
criticism, have been most illiberally manifested. 
But Liebig had laid himself open to rebuke, inasmuch as he sweepingly 
accused all physiologists of ignorance ; whereas, had he taken a correct, and not 
merely a restricted, view of a few foreign writers (forgetting the real skill and 
liberality of other men of enlightened and enlarged minds), he would have seers 
that there existed eminent physiologists who, instead of despising chemistry, were 
fully alive to its importance, and honoured it as a noble science of analysis, while they 
appreciated its powers without debasing them by endeavouring to prove too much. 
Physiology is a science of anatomical dissection ; the operator who cuts and 
carves his delicate subjects with knife or lancet, effectually destroys it. The 
chemist does no more with his tests and reagents ; neither the one nor the other 
can detect a trace of the principle of life. The tissue, the fibres, the cells, may 
be torn and rent to pieces by the instrument, or broken up by the caustic agency 
of corrosive acids, (which, by the way, is a tacit avowal of the necessity of appeal- 
ing to chemical powers,) yet the physiologist remains in profound ignorance 
of causes. 
The chemist is utterly powerless in his attempts to produce any compounds in 
the slightest degree resembling the products of vitality ; but he can effect what 
the physiologist would endeavour in vain even to conjecture : for, by analyzing 
those products, he can with surprising accuracy develop certain elements, which 
demonstrate that from a very few principles, the powers of nature produce millions 
of beautiful modifications. 
The grand combining and decomposing primary agent appears to be the light of 
the sun, or certain portions of it diffused throughout all matter in the form of those 
mysterious fluids which we term electricity and magnetism. These appear to be 
the proximate causes of attraction throughout the universe ; and to the chemist 
(the point must be ceded) belongs all the honour of the sublime discovery. 
