stain. 1

A discoloration, or a discolored spot. 2. A pigment used for staining microscopic objects such as bacteria, minute animal parasites, and sections of normal or diseased ti ues in order to make that substance capable of study under the microscope. The stains include many anilin dyes and various other chemical materials. They are described in detail in the various text-books devoted to bacteriology, pathology, histology, and medical zoology. 3. A preparation made from various anilin, vegetable, or mineral dyes, and used to color microscopic organisms and histological and pathologstudy.ical ti ues for purposes of microscopic stain'ing. The act of impregnating a substance, especially a ti ue under microscopic examinations, with pigments so as to distinguish the various structures of which it is composed. The principal s's used in microscopy are hematoxylin, carmin, ammonia carmin, pic roc arm in, silver nitrate, gold chlorid, and the various anilin dyes (fuchsin, eosin, vesuvin, auramin, safranin, fluorescin, methylene blue, genetc.). tian violet, methyl violet, malachite green, stalagmometer (stal-ag-mom'et-er). An instrument for measuring the size of drops. [Gr., stalagmos, a dropping, + metron, a measure.]