1891.1 xbo [Bdche. 



T/ie Secret of the Brotvnian Movements. 



By R. Meade Bache. 



(^Read before the American Fhitosophical Society, April 20, 18^4.) 



We first hear systematically of molecular movement, as a thing 

 directly visible, from the writings of the distinguished botanist, Dr. 

 Robert Brown, embodied in a paper entitled, "A Brief Account of 

 Microscopical Observations, Made in the Months of June, July, 

 and August, 1827, On the Particles Contained in the Pollen of 

 Plants ; and On the General Existence of Active Molecules in Or- 

 ganic and Inorganic Bodies." 



Of course we know inferentially, through physics and chemistry, 

 that the particles of bodies move under the_ influence of various 

 extraneous forces, and we know, too, that, in the case of matter in 

 a gaseous form, they move also under the influence of force inherent 

 in their own constitution. But the movements of which I am about 

 to speak relate to the visible behavior of what should be termed 

 inert matter, if that expression were not begging the question of 

 whether or not it has in itself power of motion, and thus deciding 

 it in favor of the view that it has not, but is moved by extraneous 

 force. We must begin, therefore, as is but right, by assuming that 

 it is an open question as to whether or not certain particles, in 

 aqueous suspension, call them molecules or otherwise, as one pleases, 

 organic or inorganic, but not endowed with animal life, are of them- 

 selves capable of movement, or are moved by some extraneous force 

 or forces at present unknown. The solid ground of fact from 

 which we start is that, under the conditions mentioned, they do 

 move, for that is undeniable and admitted. 



Dr. Brown soon discarded, through disproving in the course of 

 his investigations the surmise which he had made, that the particles 

 of pollen indicated by their motion a mode of function analogous 

 to that of spermatozoids, and rested eventually in the conclusion 

 that particles moving in aqueous solutions are not confined to 

 organic bodies or to their products. He had conducted a series of 

 experiments on finely crushed glass, on simple earths and metals, 

 with many of their combinations, and rocks of all ages, includ- 

 ing those in which no organic remains have ever been found. 

 Moving particles presented themselves in each of the constituent 



