Skptembkr 17, 1S96] 



NA TURE 



471 



that a microscopic crustacean, a kind of water-flea, was liable to 

 be infested by a fungus which had exceedingly sharp-pointed 

 spores. These were apt to penetrate the coats of the creature's 

 intestine, and project into its body cavity. No sooner did this 

 occur with any spore than it became surrounded by a group of 

 the cells which are contained in the cavity of the body and 

 correspond to the white corpuscles of our blood. These pro- 

 ceeded to attempt to devour the spore ; and if they .succeeded, in 

 every such case the animal was saved from the invasion of the 

 parasite. But if the spores were more than could be disposed 

 of by the devouring cells (phagocytes, as Metchnikoff termed 

 them), the water-flea succumbed. 



Starting from this fundamental observation, he ascertained 

 that the microbes of infective diseases are subject to this same 

 process of devouring and digestion, carried on both by the white 

 corpuscles and by cells that line the blood-vessels. And by a 

 long series of most beautiful researches he has, as it appears to 

 me, firmly established the great truth that phagocytosis is the 

 main defensive means possessed by the living body against the 

 invasions of its microscopic foes. The power of the system to 

 produce antitoxic substances to counteract the poisons of 

 microbes is undoubtedly in its own place of great importance. 

 But in the large class of cases in which animals are naturally 

 refractory to particular infective diseases the blood is not found 

 to yield any antitoxic element by which the natural immunity 

 can be accounted for. Here phagocytosis seems to be the sole 

 defensive agency. And even in cases in which the serum does 

 possess antitoxic, or, as it would seem in some cases, germicidal 

 properties, the bodies of the dead microbes must at last be got 

 rid of by phagocytosis, and some recent observations would 

 seem to indicate that the useful elements of the serum may be, 

 in part at least, derived from the digestive juices of the 

 phagocytes. If ever there was a romantic chapter in pathology, 

 it has surely been that of the story of phagocytosis. 



I was myself peculiarly interested by these observations of 

 Melchnikoffs, because they seemed to me to afford clear ex- 

 planation of the healing of wounds by first intention under 

 circumstances before incomprehensible. This primary union 

 was sometimes seen to take place in wounds treated with water- 

 dressing — that is to say, a piece of wet lint covered with a layer 

 of oiled-silk to keep it moist. This, though cleanly when applied, 

 was invariably putrid within twenty-four hours. The layer of 

 blood between the cut surfaces was thus exposed at the outlet 

 of the wound to a most potent septic focus. How was it pre- 

 vented from putrefying, as it would have done under such in- 

 fluence if, instead of being between divided living tissues, it had 

 been between plates of glass or other indifferent material ? 

 Pasteur's observations pushed the question a step further. It 

 now was, How were the bacteria of putrefaction kept from pro- 

 pagating in the decomposable film ? Metchnikoff s phagocytosis 

 supplied the answer. The blood between the lips of the wound 

 became rapidly peopled with phagocytes, which kept guard 

 against the putrefactive microbes, and seized them as they 

 endeavoured to enter. 



If phagocytosis was ever able to cope with septic microbes in 

 so concentrated and intense a form, it could hardly fail to deal 

 effectually with them in the very mitigated condition in which 

 they are present in the air. We are thus strongly confirmed in 

 our conclusion that the atmospheric dust may safely be dis- 

 regarded in our operations ; and MetchnikofTs researches, while 

 they have illumined the whole pathology of infective diseases, 

 have beautifully completed the theory of antiseptic treatment 

 in surgery. 



I might have taken equally striking illustrations of my theme 

 from other departments in which microbes play no part. In 

 fact, any attempt to speak of all that the art of healing has 

 borrowed from .science and contributed to it during the past 

 half-century, would involve a very extensive dissertation on 

 pathology and therapeutics. I have culled specimens from a 

 wide field ; and I only hope that in bringing them before you I 

 have not overstepped the bounds of what is fitting before a 

 inixed company. For many of you my remarks can have had 

 little, if any, novelty ; for others they may perhaps possess soine 

 interest as showing that Medicine is no unworthy ally of the 

 British Association ; that, while her practice is ever more and 

 more based on science, the ceaseless eflbrts of her votaries to 

 improve what has been fittingly designated Qua prosuni 

 omnihits arles, are ever adding largely to the sum of abstract 

 knowledge. 



NO. 1403, VOL. 54] 



SECTION A. 



MATHEMATICS AND PHYSICS. 



Opening Address by Prof. J. J. Thomson, F.R.S., 

 President of the Section. 



There is a melancholy reminiscence connected with this 

 meeting of our Section, for when the British Association last 

 met in Liverpool the chair in .Section A was occupied by Clerk- 

 Maxwell. In the quarter of a century which has elapsed since 

 that meeting, one of the most important advances made in our 

 science has been the researches which, inspired by Maxwell's 

 view of electrical action, confirmed that view, and revolutionised 

 our conception of the processes occurring in the Electro-magnetic 

 field. When the Association last met in Liverpool Maxwell's 

 view was almost without supporters, to-day its opponents are 

 fewer than its supporters then. Maxwell's theory, which is the 

 development and extension of Faraday's, has not only affected 

 our way of regarding the older phenomena of electricity, it has, 

 in the hands of Hertz and others, led to the discovery of whole 

 regions of phenomena previously undreamt of. It is sad to 

 think that his premature death prevented him from reaping the 

 harvest he had sown. His writings are, however, with us, and 

 are a storehouse to which we continually turn, and never, I 

 think, without finding something valuable and suggestive. 



'' Thus ye teach us day by day, 

 Wisdom, though now far away." 



The past year has been rich in matters of interest to physicists. 

 In it has occurred the jubilee of Lord Kelvin's tenure of the 

 Professorship of Natural Philosophy at the University of Glasgow. 

 Some of us were privileged to see this year at Glasgow an event 

 unprecedented in the history of physical science in England, 

 when congratulations to Lord Kelvin on the jubilee of his pro- 

 fessorship were offered by people of every condition and country. 

 Every scientific society and every scientific man is Lord Kelvin's 

 debtor ; but no society and no body of men owe him a greater 

 debt than Section A of the British Association ; he has done 

 more for this Section than any one else, he has rarely missed its 

 meetings, he has contributed to the Section papers which will 

 make its proceedings imperishable, and by his enthusiasm he 

 has year by year inspired the workers in this Section to renew 

 with increased vigour their struggles to penetrate the secrets of 

 nature. Long may we continue to receive from him the en- 

 couragement and assistance which have been so freely given for 

 the past half-century. 



By the death of Sir W. R. Grove, the inventor of Grove's 

 cell, we have lost a physicist whose naine is a familiar one in 

 every laboratory in the world. Besides the Grove cell, we owe 

 to him the discovery of the gas battery, and a series of researches 

 on the electrical behaviour of gases, whose importance is only 

 now beginning to be appreciated. His essay on the correlation 

 of the physical forces had great influence in promoting that 

 belief in the unity of the various branches of physics which is 

 one of the characteristic features of modern natural philosophy. 



In the late Prof Stoletow, of Moscow, we have lost the 

 author of a series of most interesting researches on the electrical 

 properties of gases illuminated by ultra-violet light, researches 

 which, from their place of publication, are, I am afraid, not so 

 well known in this country as they deserve to be. 



As one who unfortunately of late years has had only too many 

 opportunities of judging of the teaching of science in our public 

 and secondary schools, I should like to bear testimony to the 

 great improvement which has taken place in the teaching of 

 physics in these schools during the past ten years. The standard 

 attained in physics by the pupils of these schools is increasing 

 year by year, and great credit is due to those by whose labours 

 this improvement has been accomplished. I hope I may not be 

 considered ungrateful if I express the opinion that in the zeal and 

 energy which is now spent in the teaching of physics in schools, 

 there may lurk a temptation to make the pupils cover too much 

 ground. You may by careful organisation and arrangement 

 ensure that boys shall be taken over many branches of physics 

 in the course of a short time ; it is indeed not uncommon to find 

 boys of seventeen or eighteen who have compassed almost the 

 whole range of physical subjects. But although you may 

 increase the rate at which information is acquired, you cannot 

 increase in anything like the same proportion the rate at which 

 the subject is assimilated, so as to become a means of strengthen- 

 ing the mind and a permanent mental endowment when the 

 facts have long been forgotten. 



