401 Of Reason.
411 Reasoning of Insects.
435 Volition distinguishes Mankind.
456 If Knowledge produces Happiness.
466 Sympathy the source of Virtue.
485 Maxim of Socrates.
CANTO IV.
29 Oestrus or Gadfly.
33 Ichneumon fly.
37 Libellula.
39 Bees.
57 Shark.
59 Crocodile 66 Animals prey on Vegetables.
71 Defect of Stimulus.
87 Theatric Preachers.
93 Pleasure of Life, Ennui.
94 Of Tooth-edge.
119 Epidemic Complaints.
130 Compa.s.sion may be too great.
147 Doctrine of Atoms.
160 Pleasure of viewing a Landscape.
178 Pleasure from Music.
242 Ancient Orators spoke disrespectfully of the mechanic Philosophers.
270 Influence of Printing.
299 a.s.sociated ideas of three Cla.s.ses.
309 Wit defined.
349 Surprising number of Seeds.
351 Of the Aphis, its Numbers.
352 Aphis drinks the Sap-juice.
359 The Mutation of the Tadpole.
387 Animation near the Surface of the Earth.
387 All dead animal and vegetable Bodies become animated.
403 Doctrine of St. Paul.
411 Happiness increased.
417 Doctrine of Pythagoras.
431 Geology.
450 Method of investigation of Organic happiness.
453 Organic Life increases.
ADDITIONAL NOTES.
ADDITIONAL NOTES.
SPONTANEOUS VITALITY OF MICROSCOPIC ANIMALS.
Hence without parent by spontaneous birth Rise the first specks of animated earth.
CANTO I. l. 227.
_Prejudices against this doctrine._
I. From the misconception of the ignorant or superst.i.tious, it has been thought somewhat profane to speak in favour of spontaneous vital production, as if it contradicted holy writ; which says, that G.o.d created animals and vegetables. They do not recollect that G.o.d created all things which exist, and that these have been from the beginning in a perpetual state of improvement; which appears from the globe itself, as well as from the animals and vegetables, which possess it. And lastly, that there is more dignity in our idea of the supreme author of all things, when we conceive him to be the cause of causes, than the cause simply of the events, which we see; if there can be any difference in infinity of power!
Another prejudice which has prevailed against the spontaneous production of vitality, seems to have arisen from the misrepresentation of this doctrine, as if the larger animals had been thus produced; as Ovid supposes after the deluge of Deucalion, that lions were seen rising out of the mud of the Nile, and struggling to disentangle their hinder parts. It was not considered, that animals and vegetables have been perpetually improving by reproduction; and that spontaneous vitality was only to be looked for in the simplest organic beings, as in the smallest microscopic animalcules; which perpetually, perhaps hourly, enlarge themselves by reproduction, like the roots of tulips from seed, or the buds of seedling trees, which die annually, leaving others by solitary reproduction rather more perfect than themselves for many successive years, till at length they acquire s.e.xual organs or flowers.
A third prejudice against the existence of spontaneous vital productions has been the supposed want of a.n.a.logy; this has also arisen from the expectation, that the larger or more complicated animals should be thus produced; which have acquired their present perfection by successive generations during an uncounted series of ages. Add to this, that the want of a.n.a.logy opposes the credibility of all new discoveries, as of the magnetic needle, and coated electric jar, and Galvanic pile; which should therefore certainly be well weighed and nicely investigated before distinct credence is given them; but then the want of a.n.a.logy must at length yield to repeated ocular demonstration.
_Preliminary observations._
II. Concerning the spontaneous production of the smallest microscopic animals it should be first observed, that the power of reproduction distinguishes organic being, whether vegetable or animal, from inanimate nature. The circulation of fluids in vessels may exist in hydraulic machines, but the power of reproduction belongs alone to life. This reproduction of plants and of animals is of two kinds, which may be termed solitary and s.e.xual. The former of these, as in the reproduction of the buds of trees, and of the bulbs of tulips, and of the polypus, and aphis, appears to be the first or most simple mode of generation, as many of these organic beings afterwards acquire s.e.xual organs, as the flowers of seedling trees, and of seedling tulips, and the autumnal progeny of the aphis. See Phytologia.
Secondly, it should be observed, that by reproduction organic beings are gradually enlarged and improved; which may perhaps more rapidly and uniformly occur in the simplest modes of animated being; but occasionally also in the more complicated and perfect kinds. Thus the buds of a seedling tree, or the bulbs of seedling tulips, become larger and stronger in the second year than the first, and thus improve till they acquire flowers or s.e.xes; and the aphis, I believe, increases in bulk to the eighth or ninth generation, and then produces a s.e.xual progeny. Hence the existence of spontaneous vitality is only to be expected to be found in the simplest modes of animation, as the complex ones have been formed by many successive reproductions.
_Experimental facts._
III. By the experiments of Buffon, Reaumur, Ellis, Ingenhouz, and others, microscopic animals are produced in three or four days, according to the warmth of the season, in the infusions of all vegetable or animal matter. One or more of these gentlemen put some boiling veal broth into a phial previously heated in the fire, and sealing it up hermetically or with melted wax, observed it to be replete with animalcules in three or four days.
These microscopic animals are believed to possess a power of generating others like themselves by solitary reproduction without s.e.x; and these gradually enlarging and improving for innumerable successive generations. Mr. Ellis in Phil. Transact. V. LIX. gives drawings of six kinds of animalcula infusoria, which increase by dividing across the middle into two distinct animals. Thus in paste composed of flour and water, which has been suffered to become acescent, the animalcules called eels, vibrio anguillula, are seen in great abundance; their motions are rapid and strong; they are viviparous, and produce at intervals a numerous progeny: animals similar to these are also found in vinegar; Naturalist"s Miscellany by Shaw and Nodder, Vol. II. These eels were probably at first as minute as other microscopic animalcules; but by frequent, perhaps hourly reproduction, have gradually become the large animals above described, possessing wonderful strength and activity.
To suppose the eggs of the former microscopic animals to float in the atmosphere, and pa.s.s through the sealed gla.s.s phial, is so contrary to apparent nature, as to be totally incredible! and as the latter are viviparous, it is equally absurd to suppose, that their parents float universally in the atmosphere to lay their young in paste or vinegar!
Not only microscopic animals appear to be produced by a spontaneous vital process, and then quickly improve by solitary generation like the buds of trees, or like the polypus and aphis, but there is one vegetable body, which appears to be produced by a spontaneous vital process, and is believed to be propagated and enlarged in so short a time by solitary generation as to become visible to the naked eye; I mean the green matter first attended to by Dr. Priestley, and called by him conferva fontinalis. The proofs, that this material is a vegetable, are from its giving up so much oxygen, when exposed to the sunshine, as it grows in water, and from its green colour.
Dr. Ingenhouz a.s.serts, that by filling a bottle with well-water, and inverting it immediately into a basin of well-water, this green vegetable is formed in great quant.i.ty; and he believes, that the water itself, or some substance contained in the water, is converted into this kind of vegetation, which then quickly propagates itself.
M. Girtanner a.s.serts, that this green vegetable matter is not produced by water and heat alone, but requires the sun"s light for this purpose, as he observed by many experiments, and thinks it arises from decomposing water deprived of a part of its oxygen, and laughs at Dr.
Priestley for believing that the seeds of this conferva, and the parents of microscopic animals, exist universally in the atmosphere, and penetrate the sides of gla.s.s jars; Philos. Magazine for May 1800.
Besides this green vegetable matter of Dr. Priestley, there is another vegetable, the minute beginnings of the growth of which Mr. Ellis observed by his microscope near the surface of all putrefying vegetable or animal matter, which is the mucor or mouldiness; the vegetation of which was amazingly quick so as to be almost seen, and soon became so large as to be visible to the naked eye. It is difficult to conceive how the seeds of this mucor can float so universally in the atmosphere as to fix itself on all putrid matter in all places.
_Theory of Spontaneous Vitality._
IV. In animal nutrition the organic matter of the bodies of dead animals, or vegetables, is taken into the stomach, and there suffers decompositions and new combinations by a chemical process. Some parts of it are however absorbed by the lacteals as fast as they are produced by this process of digestion; in which circ.u.mstance this process differs from common chemical operations.
In vegetable nutrition the organic matter of dead animals, or vegetables, undergoes chemical decompositions and new combinations on or beneath the surface of the earth; and parts of it, as they are produced, are perpetually absorbed by the roots of the plants in contact with it; in which this also differs from common chemical processes.
Hence the particles which are produced from dead organic matter by chemical decompositions or new consequent combinations, are found proper for the purposes of the nutrition of living vegetable and animal bodies, whether these decompositions and new combinations are performed in the stomach or beneath the soil.