SCIENTIFIC HISTORY OF A PLANT. 



atmosphere, then passed into the composition of the flora of the gigantic vegetation of the 

 coal-fields — the liberated oxygen in after ages uniting itself perhaps with a mineral, form- 

 ing a sulphate — again to be reduced by organic matter to a sulphide — the carbonic acid 

 freed again, passing off into oxygen by the vegetation of the oolite — taken up into the sys- 

 tems of the icthyosaurus — that this same oxygen, for what we know to the contrary, may 

 even now be helping to carry on in us the vital process — is still at work to change again — 

 to become as pure and free as it ever was, and not different from ourselves, — never to wear 

 out or to decay, but while the world lasts to be pursuing a destiny predetermined before 

 its existence by the Great Author of nature. 



Ammonia is secreted from the body during life: it is a result of its putrefaction when 

 dead. A thousand million of the human race, besides animals, annually die. How much 

 nitrogen is thus given to plants, is a question that I think it is beyond the limit of science 

 to answer. But it comes round to us again, though not exactly in the same form; for the 

 plants supply the herbivora, who in their turn supply the carnivora. In some recent re- 

 searches, I obtained from several coffins a nitrogenized compound called adipocere, rich in 

 ammonia — in fact, an ammoniacal sap. In all cases, on opening a coffin, there Avas a 

 powerful odor of ammonia; and as an illustration of the large amount of it in this 

 adipocere, I may mention, that happening to have some in my pocket, on standing before 

 afire it began to melt; some ladies at the same time observing, "What a very strong 

 odor of hartshorn there is!" 



If all four can be represented by an oval, as some suppose — ab ova omnia — somewhat 

 on the same principle, the actions of nature might be represented by a circle. The excre- 

 ment of plants afford another exampleof circular change. Besides tho.se which are gaseous 

 and solid, there are some liquid excrements which are excreted by the roots and absorbed 

 by the soil : these fluids are very rich in carbon, so that the amount of that element which 

 is furnished to the young plant by the humus is actually, by the secretions of the grown 

 vegetable, returned again to it. 



But the greatest of all these circular changes is that which subsists between the animal 

 and vegetable kingdoms — the principles of the two systems of life requiring the refuse, the 

 one of the other. It would be altogether out of place here to mention anj' statistics as to 

 the large amount of carbonic acid derived from artificial combustion, from thermal 

 springs, from extinct volcanoes, or from the respiration of animals; but Ave know that if 

 it were not removed the atmosphere could not for any length of time support life. But 

 vegetation does this great work, and cultivation in most cases produces a purer atmos- 

 phere; so these plants serve the animal kingdom in two ways — by sui)plying it with food, 

 and by affording it a pure atmosphere. 



I can hardly conclude this sketch without making some reference to the origin of vege- 

 table life, a subject which it is well to be cautious in approaching, because of the present 

 imperfect state of our knowledge. Among the many theories of life, (so, I suppose, they 

 must be termed,) although we cannot even attempt to reach ultimate causation, I may per- 

 haps be allowed to express what may be termed a fancy of vegetable life, (for theory is 

 far too grave a term to be applied here) — a fancy of vegetable life founded upon a review 

 of Dr. Faraday's magnificent discoveries. 



The vitality of a plant forms an episode in the history of discovery, because at the first 

 animal life was regarded as totally distinct from vegetable life; but as facts accumulated, 

 analogy in functional arrangement, thoxigh brought about by a differertt form of organic 

 atus, leads us to suppose that there was but one known cause of vitality, both 

 and animals. In a plant, iheatand light are considered as necessary, but not 



