August, 1901.] 



KNOWLEDGE. 



187 



of reaching the Polo rid Smith Sound; (-1) a German 

 Expedition from Hamburg with the same object by 

 another route; {o) the " Capella " Expedition to Frauz 

 Joseph Land in search of the missing men of the Duke 

 of the Abruzzis Expedition.; (6) the Peary Expedition 

 in North Greenland; (7) the " Fram " Expedition 

 under Capt. Johaunesen, of Nansen Expedition fame, in 

 the same regions ; (S) Dr. Stein's Expedition in Ellcs- 

 mere Land, returning this year; (9) Baron Toll's 

 Expedition, which sailed last year in order to attempt 

 to reach the Pole by Xausens roiite, rid the New 

 Siberian Islands and the mysterious " Wrangel Land, " 

 and, finally (10) the Swedish Expedition to Spitzbcrgen. 

 The object of this last expedition is to measure the 

 arc of the meridian, a work commenced there last year 

 in conjunction with a Russian station in another part., 

 tlie location of which will depend on the state of the 

 ice. The expedition left Tromso, in Norway, early in 

 June, on board the well-known whaler " Antarctic," and 

 returns in the autumn, when this vessel will cany the 

 Nordenskjiild Expedition to the South Polar Continent, 

 and will thus in the same year have sailed both the 

 Arctic and the Antarctic seas. 



MEN AND MICROBES 



By E. Stenhouse, a-R-C-s,, b.sc. 



The end of one century and the beginning of a new 

 one seems an appropriate time for a stock-taking of pro- 

 gress — a time when we may usefully pause to estimate, 

 to the best of our ability, the position in nature to 

 which " civilisation '' has brought us. 



In such a mental survey at the present time nothing 

 is more striking than our recognition of the fact that 

 our daily lives are intimately bound up, for weal or woe, 

 with the activities of countless hordes of tiny beings 

 whose very existence was undreamt of a hundred years 

 ago. 



Bacteria or microbes are as ubiquitous as anything well 

 can be. They occur in the water we drink, in the air 

 we breathe, in the soil beneath our feet, and even in the 

 interior of our own bodies. Were it not for the many 

 services thej' continually perform for us, our life would 

 be quite impossible ; and, on the other hand, they have 

 been proved to be responsible for the greater number of 

 the infective diseases to which we are subject. 



So minute are the possessors of these boundless powers 

 for good and evil, that it is often necessary to magnify 

 them some 800,000 times before they can be seen at all 

 distinctly. To give some idea of this enormous magnifi- 

 cation, it may be mentioned that an ordinary cigarette 

 magnified in the same- proportion would appear seventy 

 yards long and about twenty-eight feet thick. 



A bacterium of the cigarette-shape is known as a 

 bacillus. The place of the tobacco of the cigarette is 

 taken by a jelly-like substance called protoplasm ; and 

 the cigarette-paper is represented by an envelope which, 

 however, covers in the protoplasm completely — at the 

 ends as well as at the sides of the bacillus. Many bacilli 

 possess threadlike outgrowths, by the lashing of which 

 they are propelled through any liquid in which they 

 mav find themselves. Other forms, called spiriUa, 

 move bv a serpentine twisting of their slender bodies ; 

 and yet other bacteria are globular in shape and are 

 known as cocci. When a bacterium is full grown, it 

 multiplies by breaking up into two or more pieces, 

 each of which becomes a complete bacterium. As a 



bacillus becomes adult in half an hour, or less, one 

 individual can thus give rise to about 17,000.000 in 

 twenty -four hours. When the supply of food runs short, 

 or the surroundings become in other respects unfavour- 

 able, many bacteria form themselves into spores, which 

 possess very great powers of resistance. They remain in 

 the resting stage until the hard times are over, and then, 

 with unimpaired vigour, resume their ordinary mode 

 of life. 



Of the many useful services which bacteria perform, 

 perhaps the most conspicuous is that of breaking up 

 refuse animal and vegetable matter into harmless and 

 often useful substances. That the putrefaction of organic 

 matter is really due to minute and air-borne forms of life 

 was proved conclusively by Pasteur and Tyndall about 

 the middle of the nineteenth century. It was shown 

 that if well-boiled broth is kept in vessels from which 

 the air is either wholly excluded or so admitted that all 

 floating particles are arrested, no ])utrefaction occurs, 

 and the bi-oth lemains sweet for an indefinite time. 



The importance of bacteriological research is per- 

 sistently forcing itself upon the attention of municipal 

 authorities, not only because it shows how disease- 

 epidemics may be best prevented and stamped out, but 

 also because it indicates solutions of such important 

 problems of public health as the disposal of sewage^ 

 Various modifications of the biological treatment of 

 sewage are already at work in this country, and are 

 giving very encouraging results. Essentially, the 

 process consists in passing the sewage — which may 

 previously have been partially purified by allowing the 

 grosser particles to settle in tanks — through filter-beds 

 of clinker or broken coke. A scum soon forms on the 

 coke, and microscopic examination shows that the scum 

 swarms with myriads of bacteria. The bacteria break 

 up the foul organic matter into harmless substances. 

 The efficacy of their work may be judged by the fact 

 that of several effluents I have recently analysed, the 

 putrescent organic matter had on the average been 

 reduced to less than one-seventh as the liquid was trick- 

 ling through the coke. 



It has been found that bacteria play a most important 

 part in enriching the soil with nitrates, a very necessary 

 food of plants. Generally the raw material consists of 

 the simpler compounds of nitrogen — those of ammonia, 

 for example ; but the roots of leguminous plants eontaiii 

 bacteria with the very remarkable power of taking 

 nitrogen directly from the air and putting it at the 

 disposal of the plant. 



The propriety of including yeast-cells with bacteria 

 is, perhaps, questionable ; but the indirect influence upon 

 frail humanity of these minute manufacturers of alcohol 

 is so great that they can scarcely be ignored hero. It 

 is becoming widely recognised that several species of 

 yeasts exist, and that success in brewing depends largely 

 upon the rigorous exclusion of the " wild " varieties. 



The careful work of the brewer may be biought to 

 naught in a few horns by the activities of another 

 microbe, should it gain access to the finished beverage. 

 The vinegar-organism, as it is called, attacks the alcohol 

 and changes it into acetic acid. Neither beer nor wine 

 ever " goes sour " of itself, if this little plant is absent. 

 Similarly, milk is turned sour by the lactic acid bacillus. 

 Slill others give their characteristic flavours to butter 

 and cheese ; and it has even been asserted that many of 

 the changes which tobacco undergoes in curing and 

 mellowing are due to the action of bacteria. Certain 

 workers are at present investigating this important 



