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The next question to be considered is the relation of what is termed "spontaneous generation" to the production or promotion of disease. Spontaneous generation has been and usually is taken to mean "the production of living things from materials not previously endowed with life; the term is objected to by Dr. Bastian" under the belief that any operation performed either by the action of physical or vital laws, cannot be considered spontaneous. He has proposed to employ the term "archebiosis." While I quite agree with Dr. Bastian, yet I think it better to employ the more familiar term "spontaneous generation." In approaching the consideration of this subject, I know that I am not alone treading on the domains of the special pathologist and physiologist, but also venturing on the more dangerous and sacred ground of the theologist. Now with all deference to those who object to the consideration of the question of "spontaneous generation" on the ground that it has been declared in Holy Writ that "God made heaven and earth, and the sea and all things that are therein" (Acts, xiv. 15), I must say I do not consider the inquiry impious, because the inquiry is not whether the Almighty did or did not create a particular thing, but simply how he created it.

It has been said that those who assert the truth of spontaneous generation, and the belief in the evolution of higher from lower organisms, in obedience to certain natural laws, do by such assertions disparage the creative power of God, but I cannot see that they do so on the contrary, I believe that such views imply rather a more perfect creative power in the Deity. To illustrate this: A well-trained skilful mechanist can make a watch-it may be that some engineer may even devise a machine to make a watchbut it is utterly beyond the compass of a human mind to make a series of laws which, by their working, will make a watch; and similarly I say that that Almighty power which can create a series of laws which, by their own working, will produce living organisms from formerly non-vital material, is the greatest creative power which the finite mind can imagine. I do not come before you, however, as an advocate of spontaneous generation—on the contrary, taking an impartial view of all the evidence yet produced for or against the theory, I am distinctly of opinion that at present the supporters of this theory have got the worst of the discussion, and

* Modes of Origin of the Lowest Organisms.


must produce further evidence and new facts to prove their case. I cannot possibly enter upon the discussion of the experiments which have been made with the view of proving the statements put forward on either side, but I shall refer to the more essential observations. The belief in spontaneous generation is very old. Aristotle (584, B.C.) believed in the spontaneous production of plants and animals. Harvey (1578) combated the views of the supporters of spontaneous generation, and of irregular physiological speculations generally, adopting as his maxim, "omne vivum ab ovo." Such a light seemed necessary at that time, for we find the following gravely written by Gerardes in his "Herbal," in 1597:"There are found in the north parts of Scotland, and the islands adjacent, called Orchades, certain trees, whereon do grow certain shells of a white colour, tending to russet, wherein are contained little living creatures; which shells in time of maturity do open, and out of them grow those little living things which, falling into the water, do become fowls, which we call barnacles." And, further, "but what our eyes have seen and our hands have touched we shall declare:-There is a small island in Lancashire called the Pile of Foulders, wherein are found the broken pieces of old and bruised ships, some whereof have been cast thither by shipwreck, and also the trunks and bodies, with the branches of old and rotten trees cast up there likewise, whereon is found a certain spume or froth that in time breedeth into certain shells, in shape like those of a mussel, but sharper pointed, and of a whitish colour; wherein is contained a thing in form like a lace of silk finely woven as it were together, of a whitish colour, one end whereof is fastened into the inside of the shell, even as the fish of oysters and mussels are; the other end is made fast unto the belly of a rude mass or lump, which in time cometh to the shape and form of a bird; when it is perfectly formed the shell gapeth open, and the first thing that appeareth is the foresaid lace or string; next come the legs of the bird hanging out, and as it groweth greater it openeth the shell by degrees, till at length it is all come forth, and hangeth only by the bill. In short space it cometh to full maturity, and falleth into the sea where it gathereth feathers, and groweth to a fowl bigger than a mallard and lesser than a goose." Here we have spontaneous generation and Darwinian evolution all demonstrated in a most concise and off-hand manner. It was upon such statements

as the above that the proof of spontaneous generation rested until very recent times, when the exact experiments of physicists

have been applied to, with the view of solving the question. It was affirmed that because the germs (using the term as equivalent to eggs, seeds, or spores) of the lowest organisms were not visible, that such germs did not exist; that as certain organisms are produced without such germs, and were not directly produced by organisms similar to themselves, therefore these organisms were spontaneously generated. Such a statement appeared very plausible before the invention of the microscope. That instrument, however, soon enabled us to discover that life abounded plentifully where previously it was supposed not to exist. With each improvement of the microscope more minute organisms were still discovered, and all microscopists are now agreed that there is still much outside the ken of the most perfect instrument yet inventedtherefore seeing the germs is not essential to a belief in their existence. More searching and different tests had consequently to be devised, and I shall now endeavour to sketch the lines of observation which have led up to the present state of our knowledge upon this point.

Everyone is familiar with the fact that a beam of sunlight, falling into a comparatively darkened room, has its course marked by a cloud of floating moats. The individual particles which constitute this cloud have been investigated by Professor Tyndall, the Rev. W. H. Dallinger, and others. The rough method of examining the track of a sunbeam in a room has, of course, to be abandoned, and a method devised by which particular portions of air can be tested by bright light. Professor Tyndall has provided such an arrangement in the form of a glass chamber, through which he can pass, at will, a beam of electric light. If such a beam be permitted to fall through the air of an ordinary room, the beam is marked by a luminous track, caused by the illumination of the numerous floating particles by the beam. If these particles be in any way removed, the track of the beam ceases to be luminous. The particles can be destroyed, even in the atmosphere of an ordinary room, by the simple expedient of burning them with the flame of a spirit lamp, or a red-hot poker, when the portions of the beam exposed to the heat cease to be luminous. If ordinary air, drawn from any room, be enclosed in a glass chamber, the electric beam presents luminosity. If, however, the air be filtered through cotton wool before admission to the chamber, the electric beam cannot be tracked through it. If the chamber, filled with air containing the particles I have referred to, be allowed to remain at

perfect rest for some hours, it will be found that the air, when examined by the electric beam, has become as completely purified from dust as if it had been filtered before admission to the chamber. The dust, however, is not gone, but has only subsided to the bottom of the chamber. Dallinger has found that the rapidity of the settlement of the particles is in proportion to their weight. Fluids may be tested in the same manner for floating particles, and they will subside to the bottom of the fluid. What bearing have such experiments upon the question of spontaneous generation? It is affirmed, and, I think I may say, proved, that the cloud in the air and in the fluid, demonstrated by the electric beam, contained not only inorganic particles and organic dead materials (such as pieces of clothing, hair, cuticle, dead insects, &c.), but also the germs, if not the developed forms, of low, but living organisms; and the proof consists in this, that when any air or fluid, capable of rendering the electric beam luminous, is brought into contact with any organic fluid or an artificially prepared cultivating fluid (which we may call a nutrient fluid), there will be produced in such fluid wellrecognised organic forms. On the contrary, if the air or fluid be not capable of rendering the beam luminous (the particles having been removed by filtration), such air or fluid, when brought into contact with a nutrient fluid, will not develop any living organisms, as it is what is technically termed "sterile." This is the assertion of those who disbelieve in spontaneous generation, and all their assertions have been substantiated by experiments (Pasteur, Tyndall, Dallinger, &c.). In opposition to the above view, the believers in spontaneous generation affirm that certain materials, each and all of which have been so treated as to render the presence of germs therein perfectly impossible, will (when mingled) produce living organisms. The chief investigator and supporter of this doctrine is Dr. Bastian, whose well-known abilities as a physiologist and pathologist entitle his opinions and the results of his experiments to the highest consideration. Dr. Bastian's experiments consist in the taking of certain fluids, exposing them to a boiling temperature, hermetically sealing them in glass tubes, and then showing that, without any contact with the contaminating influence of the atmosphere, living beings can be developed therein, if the materials necessary for their nourishment exist therein. Time does not

For a very good account of this subject, see paper by Professor Tyndall, in Nineteenth Century, for January, 1878.

b Loc. cit., and Beginnings of Life, 1872, &c.


permit me to detail the steps of Dr. Bastian's experiments. The main feature in all the arguments for Dr. Bastian's observations is the assumption that a temperature of 212° will destroy life, if such existed in the fluid experimented upon. Dr. Bastian's conclusion is, "that specks of living matter may be born in suitable fluids, just as specks of crystalline matter may arise in other fluids." There does not appear to me to be any reason why this may not be correct, but I do not consider that Dr. Bastian has sufficiently proved it. The most recent experiments of Tyndall and Pasteur, Dr. Bastian's great opponents (and also of Dallinger), have proved that Dr. Bastian's assumption of the destruction of life at the temperature employed by him for that purpose is incorrect. In fact Tyndall and Pasteur have pretty well disposed of all the arguments in favour of spontaneous generation founded on the belief of certain temperatures destroying life. It is admitted that bacteria and many other low forms of organic life will be destroyed by high temperatures, but these are the complete organisms-not their germs. proves that the germs are more resisting than the fully-grown organisms. This is not a surprising result, though one requiring great perseverance and trouble to prove. We know that the ova and even the partially developed embryos of the higher animals live under circumstances totally incompatible with the existence of their parents, or the beings into which these "germs" or embryos are ultimately to grow. Supposing all I have said to be correct and the conclusions true, what is the present state of knowledge with regard to spontaneous generation? Simply this-that, up to the present, spontaneous generation has not been proved. It has been proved that life may exist under the most adverse circumstances, and under conditions which were supposed to preclude the existence of living organisms. At the same time the possibility of spontaneous generation has not been disproved, although the probabilities are against its existence. Now, what bearing has this upon the origin of zymotic diseases? This, that if diseases necessarily depend upon germs, then, if we destroy the germs or their parents before they enter our bodies, we prevent disease-if we kill them after they enter, we stop or retard disease. If they are spontaneously generated they may possibly arise within the body, and precaution outside the body is useless. In any case, if it is admitted that germs are essential, their destruction will either prevent or cure disease.

It is now my duty to consider the question of "septic infection," or "septicemia," as it is usually termed. The word "septicamia"

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