248 THE AMERICAN MONTHLY [Aug. 



the corpuscles will form rouleaux like piles of coins. 

 After a time many globules lose the circular form, the 

 margins becoming irregular, or " crenated". . . . 

 To be continued. 



EDITORIAL. 



The Brownian Movement. 



What it is. — When certain very minute particles of matter 

 either organic or inorganic are held in a state of suspension in 

 fluids, very active movements of the particles may be seen un- 

 der the microscope. Gamboge has been often recommended 

 for the purpose. But of all substances, carmine made of cochi- 

 neal seems to be capable of the finest division and of the most 

 brilliant illumination, and hence best for the jnirpose. The 

 solution in water must be weak. By daylight on a back ground 

 of faint blue and by lamp light on a golden back ground, thous- 

 ands of tiny particles may be seen bright as rubies and moving 

 about over the whole field of view. The smaller the particles 

 the more vivid the movements. In alcohol, fixed and volatile 

 oils, this movement is not observable. 



The Discoverer. — The one who first called attention to it in 

 1827, was Dr. Robert Brown, a distinguislied botanist. His 

 paper was entitled : " A brief account of microscopical obsrsrva- 

 tions made in the months of June, July and August, 1827, on 

 the particles contained in the pollen of plants, and on the gen- 

 eral existence of active molecules in organic and inorganic 

 bodies." 



About a year latter he summed up his results as follows : 

 That extremely minute particles of solid m itter wliether ob- 

 tained from organic or inorganic substances, when suspended 

 in pure water, or in some otlier aqueous fluids exhibit motions 

 for which I am unable to account, and wliich, from their irregu- 

 larity and seeming independence, resemble in a remarkable 

 degree the less rapid motions of some of the simplest animal- 

 cules of infusions. That the smallest moving particles ob- 

 served appear to be spherical or nearly so, and to be between 

 1-20,000 and 1-30,000 of an inch in diameter, and that other 

 particles of greater and various size, either of similar or very 



