The uso of tears is not gemerally appreciated, even by those who shcd them most freely. It is assumed that tears are shed only occasionally as an expression of grief, thouprh tears of joy are not wbblly imknmvn. This, however, is a mistako, for the discharge of tears is contirmous, and the flow of moisture from the lachrymal glands serves as a very beautiful provisión of nature. An immense quantity of fine dust is always floating in the air, and thOTlgh this is impalpable to the visión, it would soon obscure the sight if allowed to remain in the eycs. The continuons flow of moisture irom the hu-hrvmal glanda is sufficient to keep the eyeballu clear from this accmnulation of dust, but when any grit, insect or amoke pvts into the ovos it so affei-ts the nerves as tu cause mi extra flow of toars to clear it away. Teaxs are thus involuntary, and mav be caused by any punsrent vapor, such as aribe from acida nr the odor of onions. The chief element ín the composition of a toar is water, Init with water is assoeiated minute proportiona if salt, soda, phosphate of Urne, phosphate of suda, and muciis; and when seên nul sr the microscop ■ a tear aü ir r.ition lookslike avery small fishbone. owingf to the salines forming themselves into lengthened crossliues.