SCIENCE-GOSSIP. 



175 



in which bacteriological processes are utilised for 

 man's service. The flavour of high game, the 

 taste of butter, the qualities of ripened cheese, 

 even the perfect attributes of sublime tobacco are 

 all the result of the efforts of these microscopic 

 creatures on our behalf. 



Passing from the fermentative to the putrefactive 

 organisms, we may say at once that the 

 work done by these species of bacteria is of 

 the most useful and beneficent character. That 

 a plant cannot digest the same food as a man, 

 or one of the lower animals, is evident to all. 

 Yet animal food contains the elements essential to 

 the life of the plant, arranged in a different form 

 it is true, but the same elements. It is the work of 

 the putrefactive organisms to break up complex 

 bodies, such as animal or vegetable fibre, and to 

 rearrange their constituents in such a way that they 

 may become fit food for plants. This is the process 

 which we call " decay." Some putrefactive germs 

 are to be found in air and water, but these are feeble 

 forms working with the evolution of much evil- 

 smelling gas. The true workers of the flock are to 

 be found in the soil, in the upper layers of which 

 they exist in countless myriads. The arrival of 

 dead matter in any shape or form is the signal for 

 them to commence work. It may be a withered 

 leaf or a dead bird — all comes alike to them. In 

 an incredibly short space of time the material is 

 seized upon, devoured and converted into simple 

 chemical compounds suitable for the nourishment 

 of ^vegetable life, and soon to be built up into 

 flower, plant, shrub or tree. These germs act 

 then as a connecting link between the animal and 

 vegetable kingdoms, and keep up the circulation 

 of matter from dead to living and from living to 

 dead. By their agency the decaying offal of to-day 

 becomes the green grass of to-morrow ; which in 

 turn is the beef, the man, and the silent dust of 

 the future : and so the cycle is completed. The 

 bacteria are only found in the upper layers of the 

 soil, about the upper eighteen inches ; so that 

 things deeply buried do not get the benefit of their 

 action. The gardener has learned this, and digs 

 his dressing into the surface only ; the ploughman 

 makes his furrow inches, not feet, in depth. 



One of the most recently discovered and most 

 useful powers possessed by bacteria of certain 

 forms is the conversion of sewage into harmless 

 inoffensive mud and clear water in which fish may 

 live. The sewage of Exeter and other towns has 

 been so successfully dealt with on these lines that 

 the Government recently decided to appoint a 

 Royal Commission to enquire into the subject. 

 The employment of bacteria promises to revolu- 

 tionize this branch of sanitary work. The pol- 

 lution of rivers will be a thing of the past, and an 

 annual saving of hundreds of thousands of pounds 

 will result throughout the world. It would be 



difficult to over-estimate the value of this boon 

 conferred on man by the much despised microbe. 



There is one form of earth bacillus whose action 

 has recently been investigated. This organism is 

 to be found in minute shining clusters on the 

 rootlets of leguminous plants such as peas, beans 

 and lentils. Farmers have long known that to 

 plant two crops of wheat in the same field in 

 successive years is to court failure, for the nutri- 

 tious substances of the soil have been exhausted 

 by the first. If, instead of wheat, the crop for the 

 second year be beans or lentils, the soil is found to 

 become greatly enriched, even though no manure 

 has been added, the gain consisting principally 

 in an increase of the amount of nitrogen present. 

 This nitrogen could only be obtained from the air 

 in the interstices of the soil. The agent at work is 

 a bacillus which attaches itself to the roots of the 

 plants I have named. It not only abstracts enough 

 for the use of the plant, but it is able to give off 

 the excess for the improvement of the soil, thus 

 acting as an invaluable assistant to the farmer. 

 As soon as this remarkable faculty became under- 

 stood, the growth of the microbe became an 

 industry, and to-day the nitrifying organism can 

 be bought by the bottle ; all that the farmer has to 

 do is to mix them with water and sprinkle his 

 fields. Sufficient to fertilize an acre can be bought 

 for half-a-crown. 



Phosphorescent bacilli belong essentially to the 

 putrefactive order. They may be detected fre- 

 quently on decaying fish-bones, so that these when 

 viewed in the dark, glow like the top of a wetted 

 lucifer match. 



Not all fermentative species are as beneficent 

 and harmless in their action as those I have men- 

 tioned. Some elaborate the most virulent poisons, 

 as frequent cases of food poisoning testify. Of 

 course all food contains germs. Every meal we 

 take means the swallowing of an army of harmless 

 forms ; indeed, their presence is probably essential 

 to proper digestion, for animals fed on sterilized 

 food do' not flourish, and, it is said, eventually die. 

 To be told that we are breathing and eating 

 microbes by millions need give rise to no alarm, 

 for those that have a power for evil are compara- 

 tively few, and need special conditions for their 

 multiplication. 



Just a few words in conclusion on micro- 

 organisms causing diseases in plants and animals. 

 I shall touch very lightly upon this part of the 

 subject, for, as I have said, I have no wish to lay 

 emphasis upon what might be called the criminal 

 classes in the World of Germs. Amateur gardeners 

 are painfully aware how frail a thing is plant life, 

 and with what a host of enemies it is surrounded. 

 Not the least of these are germs of various sorts, 

 such as Phylloxera, which has so often devastated 

 the vines of France, or the potato germs which 



