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1304 HUNTERIAN SOCIETY. The tendency of the research was to bring us nearer to acknowledging the possibility of the de nove production of disease, for if the bacillus could live for 174 days in soil it would be impossible to prove its previous existence in another person. Murchison certainly held this view with regard to typhoid fever. While the presence of a moderate amount of wet was favourable to the development of cholera a heavy rain was inimical, for it washed the bacilli down into the soil. Dr. WASHBOURN thought that Dr. Dempster was justified in drawing the conclusions he had done from his experiments, which confirmed in the main the work of previous workers. As to cholera, the investigations of Koch and Kitasato had shown the effects of moisture and drying on the vitality of the bacillus. Broth cultivations were dried on cover-glasses, and in three hours all the bacilli were destroyed. Kitasato made similar experiments with gelatine cultivations, which retained their vitality for a somewhat longer period. The same observers found that the bacilli remained active in a moist medium for seven months. Uffelman found that the cholera bacilli died in from one to three days in dried earth, while others had demonstrated that they would continue to multiply if added to moist soil. No multiplica- tion of the comma bacillus occurred in some kinds of non- sterilised earth. Cultures of comma bacillus added to fasces kept alive for two or three days. The results obtained with the typhoid bacillus were different. Pfuhl showed that if they were dried on a cover-glass they would live as long as eight or ten weeks, while Sternberg had shown that if they were kept moist they would live for eighteen months. Uffelman demonstrated that with dried garden earth the typhoid bacillus would remain alive for from ten to twenty-one days, and with white sand for seventy days. With moist soils Grancher and Deschamps found that they lived for three and a half months, and Karlinski, under the same conditions, found them alive for three months. The latter observer added pure cultures of typhoid bacilli to unsterilised earth and found that the bacilli died rapidly, due to the action of saprophytic organisms ; if added to putrifying fseces they retained their vitality for several months The experiments on peat were very important. He asked what was the reaction of peat and what gaits it contained, and also if it contained a number of saprophytic bacteria. Mr. WARD-HUMPHREYS said that the water-supply of Cheltenham had hitherto come from the hills, but it was now proposed to bring in a further supply from the Severn. The Worcester sewage went into the river just above the proposed intake, but the well-known preserce of peat in the Severn water might, in solution, act injuriously on any bacilli that might be present. He inquired if this surmise was confirmed by experimental observation. Dr. KENNETH MACLEOD referred to the researches of Dr. Douglas Cunningham on typhoid bacilli in milk. As long as the milk was left unsterilised the typhoid bacillus was quickly stamped out by the other organisms present, but in sterilised milk the added typhoid bacilli developed very favourably. There were a number of other factors goverring the develop- ment of bacilli : the presence of filth was perhaps of even more importance than that of moisture. He himself could not admit it to be absolutely demonstrated that the bacillus was the causa causans of cholera, though that view served as a good working hypothesis. Temperature was also impor- tant and had a good deal to do with the development of !, cholera. There were degrees of moisture unfavourable to its development ; too much moisture stopped it. Great excess and great diminution of heat were also unfavourable. Dr. CAYLEY said that typhoid fever was at present extremely prevalent amongst the English troops in India, and it prevailed under circumstances which were not con- nected with the contamination of water or of milk. It appeared indeed to be spread by dust. As Uffelman had shown that the bacillus of typhoid fever could live for ten weeks in dry earth and for forty days on dry wool, it was quite possible for bacilli in dust to be alive and active. If this were true it demonstrated the fallacy, in a dry country like India, of further developing the dry earth latrine system, for the earth impregnated with typhoid stools and spread upon the land might be one cause of the recent extension of typhoid fever in India. Mr. SHIRLEY MURPHY said that the favourable action of moisture in the development of typhoid bacilli might help to account for its constant prevalence in certain districts in the East of London. Dr. ALLAN MACFADYEN, who spoke in reply, in the absence through illness of Dr. Dempster, said that the writer was aware at the time that he started his investigations that the path he was taking was not a novel one, but the import- ance of the subject led him to pursue it. He himself was of opinion that the truth lay between the view of Pettenkofer and that of Koch. Experiments conducted upon the surface soil were most important because the surface soil was most. likely to be contaminated by pathogenic organisms from man, &c., and, acting as it did as an efficient filter, it retained a large number of such organisms in its upper layers. The deeper layers of the surface soil did not possess a suitable temperature for the continued life of pathogenic bacteria, and, again, the influence of saprophytic bacteria was only exerted in the uppermost layers ot the soil. For practical purposes the surface soil could be regarded as consisting of three layers : (1) the extreme superficial layer, which was usually either very dry or very moist ; (2) an intermediate layer, which was always damp, and which did not admit of evapora. tion ; and (3) a deeper layer, lying immediately above the subsoil, which was kept wet by capillarity from the subsoil. The three factors to be considered in studying the questions raised in the paper were the soil, the water, and the action of other bacteria The paper itself dealt with the first two of these, and with regard to the third a later communication would be made ; but they had ascertained already that cholera organisms would live in soil a long time side by side with saprophytic organisms. Dr. Dempster’s experiments differed a little from Uffelman’s, but these differences might depend upon the number of bacteria used and the varying resisting power of the different samples of micro-organisms. Peat contained a large number of spores of bacteria, and a point for their future investigation would be to compare the- number of bacteria present in peat with those in other soils. The peat was acid in reaction, and some complex soil acids were present. At present no direct experiments had been made with peat in solution. They were now engaged in working out the effect of the presence of filth on the growth of the micro-organisms. There was evidence to show that temperature also played an important part. The presence of summer beat and of a salt solution lengthened the life of a comma bacillus. In conclusion Dr. Macfadyen bore testimony to the patience with which Dr. Dempster had conducted these experiments, and he wished also to express his gratitude to Mr. Cobb, the founder of the scholarship, who had so, generously defrayed the expenses of this important research, HUNTERIAN SOCIETY. Adjourned Discussiott on Diphtheria.’ THE adjourned discussion on Diphtheria was held on May 5th, Mr. C. J. SYMONDS in the chair.-Mr. ST. CLAIR B. SHADWELL said that he was medical officer of health of one of the eastern suburbs divided frcm London by the river Lea. The annual number of deaths from diphtheria bad been few, and in 1870 and 1872 there had been no such deaths at all. Between 1873 and 1879 the number amounted to about three annually. From 1880 to 1886 (1880 being a memorable year in the history of the district, inasmuch as it was then that the present system of drainage was entered upon) the annual number of deaths averaged ten. In 1887 there was a sudden rise, equal to a, death-rate of 1 5 per 1000, and in 1888 of 1 7. Since that date the rate bad gone down, and for some years it had been 0 6 per 100O.-The Medical Omcer of Health of Plum- stead held very strongly that the great cause of the spread was the ventilation of the sewers into the road. The speaker thought it was quite possible that water might sometimes serve as the vehicle and referred to the case of a lad employed at a dairy, who contracted diphtheria and was placed in a room the floor of which had wide crevices, and beneath it was the water cistern. It was impos- sible to prove that the water was really contaminated, but the fact remained that seven other persons in that house caught the disease. The only domestic animal that appeared to him to have any share in disseminating the disease was the cat, and a few instances of this had come to his notice. Skilled opinion at present tended to regard bad smells as not having much to do with the causation of the disease. He then showed on the screen a rough plan of the district, pointing out how the disease had 1 Continued from p. 1140.
