SUFFICIENT has already been said to indicate how closely the existence of microscopic fungi and bacteria are bound up with our daily lives. But the method in which they impinge on our domestic activities is no less startling. The whole process of cooking, for example, has as one of its objects, not merely the rendering of food more digestible or more palatable, but the sterilisation of it by the application of heat, so that it can be kept for a longer period before ‘going bad.’ ‘Going bad ‘is much more bacterial or fungal decay than an actual chemical breakdown of the food substances. We have to obviate the effects of fungi and bacteria in various ways. Tea is a dried; if kept moist it will develop an abundant growth of micro-organisms, and it is possible occasionally to find developing inside the tea-caddy. The bottling of fruit depends for its success on sterilising the material by heat. When jam is made the product must have so high a concentration of sugars that micro-organisms are unable to grow in it.
‘LEPROSY OF A HOUSE’
SOME mention should be made of fungus diseases that can assail the actual fabric of a house. If a house is damp, mildews will grow on the wall-paper and on pictures and books. They will cover boots in an undisturbed cupboard and will attack curtains, cretonne covers, furniture, towels and dusters. The sinister ‘dry-rot ‘disease of timber,
which is caused by a fungus, is one that often proves expensive to harbour. It is invariably a product of damp conditions, as like all other fungi it cannot grow unless it is supplied with certain minimum quantities of air, moisture, heat and food-materials. The food material is the woodwork of the house, and from the point of view of the fungus all timber in a house is as one, whether it be a joint, floorboard, wall panelling or ceiling-lath; all can be attacked unless protected by a layer of creosote or some other preservative.
House owners are often puzzled to find that the point of attack is a long way from the source of the infection. The fungus will usually have some wet place as its base of operations from which the attack has commenced. When it has extracted from any piece of woodwork all that it can usefully extract, the fungus will form long cords that may travel considerable distances through brickwork, concrete, or inside pipes, until they find some more food-material—that is, unprotected wood.
It may be said in passing that paint offers but little hindrance to the triumphant progress of the fungus. The method of ridding a house of this dangerous pest is first to destroy all infected material by burning, to protect all unprotected woodwork and to take the necessary steps to secure an efficient ventilation by a circulation of dry air. The disease is so widespread that it is impossible to avoid infection, so to protect a house an effort must be made to ensure that infection cannot develop.