September 17, 1896] 



NA TURE 



465 



the purpose of supplying to the growing plant certain chemical 

 ingredients not contained in the sugar but essential to its nutri- 

 tion. And the correctness of this view he confirmed in a very- 

 striking manner, by doing away with the fibrin or other animal 

 material altogether, and substituting for it mineral salts contain- 

 ing the requisite chemical elements. A trace of the grey deposit 

 being applied to a solution of sugar containing these salts in 

 addition to the chalk, a brisker lactic fermentation ensued than 

 could be procured in the ordinary way. 



I have referred to this research in some detail because it 

 illustrates Pasteur's acuteness as an observer and his ingenuity 

 in experiment, as well as his almost intuitive perception of 

 truth. 



A series of other beautiful investigations followed, clearly 

 proving that all true fermentations, including putrefaction, are 

 caused by the growth of micro-organisms. 



It was natural that Pasteur should desire to know how the 

 microbes which he showed to be the essential causes of the 

 various fermentations took their origin. It was at that period a 

 prevalent notion, even among many eminent naturalists, that 

 such humble and minute beings originated de iicn'o in decompos- 

 ing organic substances ; the doctrine of spontaneous generation, 

 which had been chased successively from various positions which 

 it once occupied among creatures visible to the naked eye, 

 having taken its last refuge where the objects of study were 

 of such minuteness that their habits and history were correspond- 

 ingly difficult to trace. Here again Pasteur at once saw, as if 

 by instinct, on which side the truth lay ; and perceiving its 

 immense importance, he threw himself with ardour into its 

 demonstration. I may describe briefly one class of experiments 

 which he performed with this object. He charged a series of 

 narrow-necked glass flasks with a decoction of yeast, a liquid 

 peculiarly liable to alteration on exposure to the air. Having 

 boiled the liquid in each flask, to kill any living germs it might 

 contain, he sealed its neck with a blow-pipe during ebullition ; 

 after which, the flask being allowed to cool, the steam within it 

 condensed, leaving a vacuum above the liquid. If, then, the 

 neck of the flask were broken in any locality, the air at that 

 particular place would rush in to fill the vacuum, carrying with 

 it any living microbes that might be floating in it. The neck of 

 the flask having been again sealed, any germs so introduced 

 would in due time manifest their presence by developing in the 

 clear liquid. When any of such a series of flasks were opened 

 and resealed in an inhabited room, or under ihe trees of a 

 forest, multitudes of minute living forms made their appearance 

 in them ; but if this was done in a cellar long unused, where the 

 suspended organisms, like other dust, might be expected to 

 have all fallen to the ground, the decoction remained perfectly 

 clear and unaltered. The oxygen and other gaseous constituents 

 of the atmosphere were thus shown to be of themselves incapable 

 of inducing any organic development in yeast-water. 



Such is a sample of the many well-devised experiments by 

 which he carried to most minds the conviction that, as he 

 expressed it, ia ghu'ralion spon/aiu'e est une chimtre, and 

 that the humblest and minutest living organisms can only 

 originate by parentage from beings like themselves. 



Pasteur pointed out the enormous importance of these humble 

 organisms in the economy of nature. It is by their agency that 

 the dead bodies of plants and animals are resolved into simpler 

 compounds fitted for assimilation by new living forms. Without 

 their aid the world would be, as Pasteur expresses it, emoinbre 

 de iadavres. They are essential not only to our well-being, but 

 to our very existence. Similar microbes must have discharged 

 the same necessary (unction of removing refuse and providing 

 food for successive generations of plants and animals during the 

 past periods of the world's history ; and it is interesting to think 

 that organisms as simple as can well be conceived to have existed 

 when life first appeared upon our globe have, in all probability, 

 propagated the same lowly but most useful oflfspring during the 

 ages of geological time. 



Pasteur's labours on fermentation have had a very important 

 influence upon surgery. I have been often asked to speak on my 

 share in this matter before a public audience ; but I have hitherto 

 refused to do so, partly because the details are so entirely 

 technical, but chiefly because I have felt an invincible repug- 

 nance to what might seem to savour of .self-advertisement. The 

 latter objection now no longer exists, since advancing years have 

 indicated that it is right for me to leave to younger men the 

 practice of my dearly loved profession. And it will perhaps be 



NO. 1403, VOL. 54] 



expected that, if I can make myself intelligible, I should say 

 something upon the subject on the present occasion. 



Nothing was formerly more striking in surgical experience 

 than the difference in the behaviour of injuries according to- 

 whether the skin was implicated or not. Thus, if the bones of 

 the leg were broken and the skin remained intact, the surgeon 

 applied the necessary apparatus without any other anxiety than 

 that of maintaining a good position of the fragments, although 

 the internal injury to bones and soft parts might be very severe. 

 If, on the other hand, a wound of the skin was present com- 

 municating with the broken bones, although the damage might 

 be in other respects comparatively slight, the compound fracture, 

 as it was termed, was one of the most dangerous accidents that 

 could happen. Mr. Syme, who was, I believe, the safest 

 surgeon of his time, once told me that he was inchned to think 

 that it would be, on the whole, better if all compound fractures 

 of the leg were subjected to amputation, without any attempt to 

 save the limb. What was the cause of this astonishing differ- 

 ence ? It was clearly in some way due to the exposure of the 

 injured parts to the external world. One obvious effect of such 

 exposure was indicated by the odour of the discharge, which 

 showed that the blood in the wound had undergone putrefactive 

 change by which the bland nutrient liquid had been converted 

 into highly irritating and poisonous .substances. I have seen a 

 man with compound fracture of the leg die within two days of 

 the accident, as plainly poisoned by the products of putrefaction 

 as if he had taken a fatal dose of some potent toxic drug. 



An external wound of the soft parts might be healed in one of 

 two ways. If its surfaces were clean cut and could be brought 

 into accurate apposition, it might unite rapidly and painlessly 

 " by the first intention." This, however, was exceptional. Too 

 often the surgeon's efforts to obtain primary union were frustrated: 

 the wound inflamed and the retentive stitches had to be removed, 

 allowing it to gape ; and then, as if it had been left open from 

 the first, healing had to he efi'ected in the other way which it is 

 necessary for me briefly to describe. An exposed raw surface 

 became covered in the first instance with a layer of clotted blood 

 or certain of its constituents, which invariably putrefied ; and the 

 irritation of the sensitive tissues by the putrid products appeared 

 to me to account sufficiently for the inflammation which always 

 occurred in and around an open wound during the three or four 

 days which elapsed before what were termed "granulations" 

 had been produced. These constituted a coarsely gianular 

 coating of very imperfect or embryonic structure, destitute of 

 sensory nerves and prone to throw off matter or pus, rather than 

 absorb, as freshly divided tissues do, the products of putrefac- 

 tion. The granulations thus formed a beautiful living plaster, 

 which protected the sensitive parts beneath from irritation, and 

 the system generally from poisoning and consequent febrile 

 disturbance. The granulations had other useful properties of 

 which I may mention their tendency to shrink as they grew, thus 

 gradually reducing the dimensions of the sore. Meanwhile another 

 cause of its diminution was in operation. The cells of the epidermis 

 or scarf skin of the cutaneous margins were perpetually produc- 

 ing a crop of young cells of similar nature, which gradually 

 spread over the granulations till they covered them entirely, and 

 a complete cicatrix or scar was the result. Such was the other 

 mode of healing, that by granulation and cicatrisation ; a process 

 which, when it proceeded unchecked to its completion, com- 

 manded our profound admiration. It was, however, essentially 

 tedious compared with primary union, while, as we have seen, 

 it was always preceded by more or less inflammation and fever, 

 sometimes very serious in their effects. It was also liable to 

 unforeseen interruptions. The sore might become larger instead 

 of smaller, cicatrisation giving place to ulceration in one of its 

 various forms, or even to the frightful destruction of tissue which, 

 from the circumstance that it was most frequently met with in 

 hospitals, was termed hospital gangrene. Other serious and 

 often fatal complications might arise, which the .surgeon could 

 only regard as untoward accidents and over which he had no 

 erticient control. 



It will be readily understood from the above description that 

 the inflammation which so often frustrated the surgeon's 

 endeavours after primary union was in my opinion essentially 

 due to decomposition of blood within the wound. 



These and many other considerations had long impressed me 

 with the greatness of the evil of putrefaction in surgery. I had 

 done my best to mitigate it by scrupulous ordinary cleanliness 

 and the use of various deodorant lolicns. But to prevent it 



