DR. BASTIAN'S EXPERIMENTS ON THE ORIGIN OF LIFE.
THE question whether vitality and organisation are capable of being evolved from dead matter, or must always proceed from a previously existing organism, is one which is older than Lucretius, as a matter of speculative thought, and as one of ex- perimental investigation is at least as old as Redi and Spallanzani. Of late years it has again occupied the attention of physiologists, and has been made the subject of laborious research and much con- flict of opinion, and the occasion of not a little acrimony. On the affirmative side of the controversy, or that on which the pos- sibility of life being produced without ordinary generation in any of its modes is maintained, our countryman, Dr. Bastian, is the foremost champion ; and on the other, the well-known French physiologist, M. Pasteur, supported by the high authority of Professor Tyndall. The• maxim, Omne victim ex oro, which was once held to be expressive of an ascertained truth, is now abandoned ; and now the wider generalisation, Omne vivum ex vivo, is on its trial. It has long been matter of notoriety that certain vegetable infusions and certain animal secretions, in the act of becoming putrid, swarm with microscopic beings endowed with great activity, and capable of reproducing their kind by the fissiparous process, or self-division. The most pro- minent and typical varieties of these organisms are called Bacteria. That they are endowed with vitality nobody doubts ; whether they are animals, or .belong to a third division of things, called by some Protozoa, a sort of com- mon starting - point from which both animals and plants branch off in different directions, is of little moment. The usual hypothesis has been that certain "germs " of these creatures abound in the atmosphere and everywhere, and develope themselves whenever they fall into a suitable nidus, such as the decomposing fluids just mentioned. These germs, be it ob- served, are entirely hypothetical, being, if they exist at all, ultra- microscopic. The experiments which have been made to test the mode of production of the Bacteria have all been devised on the general principle of exposing the fluids in which they appear, to a degree of heat such as it is supposed no living thing or germ can sustain, while, at the same time, precautions are taken to exclude contact with the air or other medium by which the supposed germs could be introduced. M. Pasteur, some fifteen years ago, announced as the result of his experiments that the germs could sustain, in the ordinary state of the fluids in question, which is more or less acid, a temperature of 100° Centigrade, but that if the fluid were rendered neutral by the addition of a little alkali, they survived up to the point of 110°. During the last few years, Dr. Bastian has made innumerable experi- ments, and in his own belief, at least, with great care and delicacy, heating his fluids (an infusion of turnip, mixed with a little cheese-powder, is one of the best) in glass flasks, whose mouths are drawn out to a fine point, and after the liquid has repeatedly spurted out by boiling and the air is ex- hausted, are hermetically sealed with the blow-pipe. After being exposed to a temperature above that of boiling water, in some cases as high as 125°, or even 150° C., he finds bacteria abundantly produced. So far, the phenomena were capable of explanation on either hypothesis. The negative side could hold that Dr. Bas- tian had merely raised some degrees higher the point in which germs can live, while the affirmative side could con- tend that it was incredible that any living thing, germ or otherwise, could survive such an ordeal, and that the organisms must have been produced de novo from the fluids. Dr. Bas- tian's further and more complex experiments, taken by them. selves, certainly tend to incline the balance to the affirmative side. For example, he assumes, not unnaturally, that if a fluid is found swarming with bacteria rapidly multiplying, their germs, if such exist at all, will be found in it at all stages of de- velopment. He finds by experiment that there are certain solu- tions of saline matter in which a drop of this putrifying fluid will produce rapid multiplication of bacteria, although if left to themselves and duly protected, they will never give rise to life at all. He also finds that these saline fluids lose their power of multiplying life by exposure after inoculation to a certain com- paratively moderate temperature (158° Fahr.). He infers from this that bacterial life, whether adult or in the form of germs, is destroyed by the degree of heat just mentioned, which is far below that to which the other fluids have often been exposed, and yet have, after cooling, become peopled with these organisms, though completely protected from atmospheric or other contami- nation, and that therefore in the latter case the fluids themselves must have evolved the living beings without the assistance of germs of any kind. M. Pasteur, although he admits Dr. Bastian's facts up to a certain point, still adheres to the germ hypothesis, and has challenged his rival to exhibit certain of his processes before MM. Dumas, Milne-Edwards, and Boussingault. The challenge has been accepted, and the physiological world awaits the trial and the verdict with much interest. The chal- lenge specially refers to a process by which Dr. Bastian thinks he has tested M. Pasteur's theory—that germs are killed by exposure to 100° C. if the fluid is acid, but that a mixture of alkali pro- tects them up to 110°—and proved that the result will take place even when the original acid fluid has been heated to its own acknowledged death-point, and the alkali to a much higher degree, the two substances being afterwards, by a very neat arrangement, mixed so that neither can have suffered any exposure to the air subsequent to the heating process. The supposed germs being thus, ex concessis, dead in both fluids before they are combined, Dr. Bastian contends that the genesis of life from what is not living has been proved to take place in the neutralised fluid.
Of the numerous other persons who have recently carried through a series of analogous experiments, by far the most con- spicuous is Professor Tyndall, some of whose results have been briefly alluded to in this journal. In particular, both he and Dr. Robertson, of Manchester, have repeated Dr. Bastian's last- mentioned process, with this modification,—that the alkaline fluid was raised by them to a yet higher temperature (which in
no way interferes with its chemical constitution), while the putrescible fluid was allowed fair-play by being boiled for a shorter period. Nevertheless, no bacterial life appeared. Two years ago, Professor Tyndall performed many times Dr. Bastian's. simpler process, with a like negative result ; but last year, in the laboratory of the Royal Institution, after boiling certain putrescible fluids for fifteen minutes, with the usual precautions, abundant organisms were produced, thus apparently confirm- ing Dr. Bastian's views. This Professor was led to attribute to the air of the rooms being so intensely impregnated with the sup- posed germs (believed to originate in a quantity of old hay) as to resist his precautions. To test this, he caused exactly similar fluid to undergo the same process at Kew, where a purely nega- tive result was obtained ; and also repeated the experiment in a shed on the roof of the Royal Institution, with fluid which had never been near the laboratory. The result was positive. It was remembered, however, that his assistants had worn clothes which had passed through the latter place ; on changing their clothes and purifying the shed, no organ- isms appeared. All this no doubt pointed strongly in the direction of the germal theory, but implied that the precaution taken to guard the fluid from atmospheric contamination had been imperfect, both in Dr. Bastian's processes and in those in the laboratory and study. Professor Tyndall has now formed a hypothesis which obviates this objection. He thinks that among the multitude of germs contained in a given fluid, some, being those nearer maturity, are soft, and are destroyed by a comparatively low temperature ; while others in various earlier stages of growth are more or less indurated, and resist stronger measures. He, therefore, in place of one continuous boiling, subjects the fluid to several successive heatings, at in- tervals of ten or twelve hours, thus catching each successive crop of germs as it arrives at the stage of non-resistance, and finally extinguishing the whole. Each of these exposures to heat requires, he says, only an extremely brief period of endur- ance. This is very ingenious, and tallies exactly with the germ- hypothesis. Here the controversy at present stands. We do not know whether the testing process before the French Commis- sioners, if it takes place, will be extended beyond its original scope, so as to embrace some of the more recent observations, but it would be of great advantage to the investigation could this be done. Professor Tyndall summed up his lecture at the Royal Institution on the last evening of this season by declaring that after many months of elaborate experiment, he was convinced that, from the beginning to the end of the inquiry, there has not been a shadow of evidence in favour of spontaneous generation. The mode of production of these simple little organisms may appear to the unscientific a comparatively trifling matter, but it in- volves issues of the deepest importance. If it shall be satis- factorily proved that life and organisation, even in their humblest forms, can be evolved from dead matter, and still more, if they can take place in matter which has never been in the vital or organised state of combination, it will revolutionise the whole of our ideas of the mutual relation of chemical and vital action. Even to those who persist in asking Cui bond ? in regard to every scientific in- quiry, we may point out that the question has a most important practical side, in its obvious bearing on the origin and prevention of zymotic diseases. If the production of bacterial life by the infec- tion of its germs should be proved to be the cause of putrefaction, it is presumable that the unknown germs which are supposed to pro- duce these maladies are so far analogous to those of the Bacteria and the allied organisms, that any knowledge we may attain to in regard to the history of the latter, and the means which may be used to render them inert, will throw no small light upon the former, and the present investigation may be the beginning of some of the most brilliant improvements of the healing art. It has, of course, a still more direct relation to the more homely art of preserving food from decomposition. Nor will its practical utility disappear even should it be found that these organisms are the effect of putrescence rather than its cause, which is the view necessarily held by the advocates of spontaneous generation. In this controversy, as in almost every other, there arises, in limine, a question of onus probandi ; and although the true result can only be the fruit of patient and elaborate experiment, it is impossible entirely to shut our eyes to the a priori view of the whole matter. At first sight, the burden of proof certainly appears to lie upon those who announce the possibility of a devia- tion from what we know to be the usual manner in which indi- viilual organisms are produced, but there are one or two weighty considerations which, although they do not shift the onus, must have, for every reasonable mind, the effect of somewhat diminish- ing the strength of the presumption with which the negative party starts. The popular mind has been long accustomed to look upon the original creation of living beings as in some vague sense miraculous. We presume that no educated person now entertains this very crude conception, or believes that it is essen- tial to theism, or even to ordinary orthodoxy of belief. It is obvious that whatever may have been the details of the genesis of life on this or any other planet, it must have taken place in accordance with rule or law,—a law which must come into operation whenever similar conditions combine. It is univer- sally admitted that the earth was at some remote period utterly unfit to be the abode of life, even in its most rudimentary shape, and it is not improbable that at various successive epochs it has again been reduced to that condition. Organisation must, there- fore, have had at least one, if not many, beginnings on its sur- face. One distinguished savant, indeed, has, assuming the impossibility of the derivation of life from what is not living, been driven to the astounding conjecture that life may, in some of its humbler forms, have been introduced into our earth by germs carried by aerolites out of remote space. The conjecture is as far-fetched as the aerolites themselves ; moreover, it only removes the difficulty a step backwards, unless we suppose organisation to have been eternal. If there are laws of nature in accordance with which life has been called forth out of inorganic matter at one or several distant periods of time, there is surely no great improbability that the conditions requisite for that process should in some degree and in obscure corners still exist. The law cannot be altered, and as to the conditions at the distant epochs in question, we know little about them ; but we certainly have no warrant for assuming that they were so completely different in kind, as well as degree, from those under which we now live, as to render a process which must then have taken place on a huge scale absolutely impossible now. To a thorough evolutionist, the presumption against spon- taneous generation must appear smaller than to one who has not accepted that creed. We, at all events, have only to join in the hope expressed by the author of an article on this subject which appeared in the April number of the Contemporary Review, that the coming investigation will be conducted with the calmness and impartiality, and absence as well of national as of personal feeling, with which it is becoming to approach one of the most mysterious and important secrets of Nature.
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