A magnifying instrument. A high power optical microscope will discern organisms as small as bacteria, but smaller organisms (e.g., viruses) require the considerably greater magnifying power of an electron microscope. See also: Dissecting microscope. Microscopic
Too small to be seen with the naked eye. Microsphaera
A genus of the Erysiphales (powdery mildews) characterised by cleistothecia that contain several asci, and appendages that dischotomise several times at the tip. The main species of economic importance are M. alphitoides (oak mildew), M. berberis, (barberry mildew) and M. grossulariae (Gooseberry mildew).
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