OIDIUM, nyi4vrnnW (Nvo-Lat., from Gk. Lbov, Son, egg). The conidial form of certain Ery sipheie, an important family of minute fungi growing on animal and vegetable substances. The species of Oldham consist of tiny tubular white or bright colored threads, forming flocks, simple or irregularly branched, assuming, in their upper part the form of strings of beads, which finally break up into elliptic spores. Oidium alhicans is found on the epithelium in the mouth and throat in the disease called a ph tine, or thrush. It is more common in children and aged persons than in those who are in the prime of life. Another species, Oidiunt Tuckcri, which has attracted great attention in Europe, is regarded by many as producing a destructive grape disease. It is the conidial form of Unci nula 'locator, or Uneinula spiral is. It makes its appearance at first in the form of a mycelium of creeping, filaments, which send out upright or dchnnbent jointed stems. Each bead like joint of the stems develops into a sort of spore, munbers of which are finally discharged in little clouds. The grape disease was first ob
served in Kent, England. in the spring of 1845. The disease rapidly spread over other English vineries; was observed about the same time in the vineries of Pat-is, and soon in the vineyards of almost all parts of France, Italy, Greece. Tyrol, and Hungary, finally, and in a slighter degree, affecting the vineyards of the Ilhine. Its ravages extended to Algeria, Syria, Asia Minor. and many other countries, among which is par ticularly to he noted the island of where it proved almost completely destructive to the grapes and nearly put an end to the prodnctim of the celebrated Madeira wine, It is probable that the eomplete isolation of the Madeira vine yards made the progress of the disease more rapid, and its result more complete th:m else where, by reason of the prevalence of the condi tions favorable for it. This disease is more fnlly deseribed under GRAPE as powdery mildew, for which remedies ate there suggested.