Page:The American Cyclopædia (1879) Volume VI.djvu/700

 688 EPIPHYTES udders of cows. Let any room remain undis- turbed for any length of time, and then ex- amine the dust which has collected, and multi- tudes of vegetable spores will be found. We know not but in each breath of air we inhale, each draught Ave raise to our lips, are lurking germs which, if they find a proper nidus, may make of us a dwelling place. Among the most important of the vegetable parasites of man is Oidium albicans. the oidium allicans, which belongs to the same genus as the fungus which has proved such a destructive pest to the vineyards of southern Europe and Madeira, viz., the oidium Tuclceri. It forms the disease called aphthse, which shows itself on the mucous membrane, generally on the tongue of infants, as a soft, white, pasty, slightly elevated patch. On the lips, where it becomes dry, it forms dark brown crusts. Its seat is first the upper surface of the epithelial cells, but soon its filaments penetrate deeply between them, and can no longer be removed by art. It is found also in the nose, windpipe, stomach, and intestine. It may occur in per- sons of every age, but especially occurs in young children and the old, owing to the liquid form of their food, which allows any accumulation in the mouth to remain undisturbed, and to the long sleep necessary to these ages. It is of frequent occurrence also in the last stages of many diseases, when the mucous membrane is covered with nitrogenous, decomposable matter. According to Kuchenmeister, its appearance is due to catarrh of the mucous membrane, which is very common in old age and infancy, and this is without doubt the most frequent predis- posing cause. Robin accounts for its presence on the nipples of nurses by the supposed lactic acid reaction produced there, but it is more probable that the disease is transferred thither with the mucus from the child's mouth, and becomes attached by the extension of the mycelium into the epithelium. Oidium has also been found in the nails and on the surface of ulcers. On diphtheria this parasite is found to be a constant attendant. Whether its pres- ence causes the inflammation of the throat, or is merely the result of a proper nidus offered it by this specific disease, is not easy to deter- mine. In other cases it seems to give little trouble as a general rule, though in very young children it may produce difficulty of breathing and swallowing. The ulceration which is sometimes found is probably caused by the accompanying catarrh. That it is con- tagious is shown by its rapid spread in large foundling asylums, and by direct experiment. Its general transference from one mouth to an- other in such localities is easily understood when we consider their customs the nipple taken from one child and given to another, feeding various children with the same spoon, and so on. How it appears in sporadic cases also is not difficult to explain, believing as we do that it is an ordinary form, which may grow on many substances, and be transported in the form of its sporules in all directions by the air. The diseases caused by these parasites may be divided into three groups : those of the alimen- tary canal, of the scalp, and of the skin. In the first we place the oidium albicans already de- scribed, and here too belongs the torula cerevi- sicBj or yeast plant, its near relative, which is met with occasionally in all the fluid excretions of the body. It forms the ordinary cholera fungus in the vomitus and intestinal discharges of this disease, and is often found in the stom- ach and attached to the walls of the intestine after death. Its usual presence in fermenting fluids has led to the belief that it was the cause of such change, and we know that when added as yeast it acts as a true ferment ; but we do not know but that the peculiar chemical change may offer merely the conditions for its sudden Merismopasdia ventriculi. appearance and rapid growth. It is another form of the penicillium glaucum. Another plant, found most commonly in the fluid of the stomach, is the merismopcedia (or sarcina) xen- triculi, which has been usually placed among the algae. It has been found also in the urine, in the intestinal canal, and in the lungs. Its presence in the stomach of man probably causes no symptoms whatever ; it has been cultivated