28 THE AMERICAN MONTHLY [Jan. 



ill};- jj^crms. There remain in the ui)j>araUis, then, inferior 

 oxidesol niaiig-unese, which hasten to re-oxidize themselves 

 and furnish ag"ain a certain ([uantityof manjj-anesc dioxide; 

 tile water as thus tinally j)urified contains a little lime in 

 the form of bicarbonate and traces of oxygenated water. 

 A very small <|uantity of calcium permang-anate is used in 

 this process, and. if jiracticable on a larg"e scale, is of great 

 importance. Water having- 100,000 colonies of microbes 

 can thus be ])uritied, it is stated, and ice placed in water 

 with calcium ])ermanganate is also quickly sterilized. — 

 American Druggist. 



BACTERIOLOGY. 



The Microbic Character of Acute Catarrhal Otitis Media. 

 — Lannois concludes from his observations that: 1. The 

 normal middle ear in animals acts like an aseptic cavit}' 

 and contains no micro-organisms. 2. The liquid of catarr- 

 hal otitis media does or does not contain microbes, accord- 

 ing- to the ]»eri<»(l at which it is examined after the begin- 

 ning-. .V The disai)pearance of the microbes is sometimes 

 probably due t<i the bactericidal power of the mucous mem- 

 brane and the mucus. 4. The bactericidal action explains 

 why the secretion rarely becomes purulent, even after 

 paracentesis and repeated catheterization. 



MICROSCOPICAL SOCIETIES. 



Sheffield Microscopical Society. 

 Kridav, December IStli. Mr. (r. T. W. Xcwsholmc, 

 Ilonorarv Secretar\, in the chair, 'i'he President, Mr. A. 

 M. Allen, lectui-ed on "The l*hilosoi)hy of the Microscope." 

 He explained tlial he had cliosen tliat subject because some 

 peo])le were at sea as to the optical jirinciples involved in 

 the use of the microscoi)e. He reminde*! the gathering 

 that we do not see light in theordinar\- sense. l)Ut ]")ercei\e 

 it when it falls on something capable of reflecting it, and so 

 reaches the eye. Another principle to which he called at- 



