1892.] NEW-YORK MICROSCOPICAL SOCIETY. 7 



discovery of the ceaseless activity, under favorable circumstances, 

 of probably all small particles having a diameter of less than the 

 one-five-thousandth of an inch. This phenomenon, which has 

 come to be known as "the Brownian movement," but the cause of 

 which has never been determined, might easily deceive the inex- 

 perienced observer into thinking he had under the microscope a 

 lively colony of animalcules when, in fact, he might be looking at 

 almost any finely-divided insoluble substance, — even, perhaps, at 

 iron filings. In 1874 I rubbed up in water a little gamboge, 

 which I confined in a hermetically-sealed cell, and which, for 

 more than fourteen years (as long as the cell remained intact), 

 was brought out periodically to illustrate the fact that " things' 

 are not what they seem." Numerous other illustrations of this 

 uncertainty of appearances might be drawn from things in sight 

 and above sight, as well as beneath sight ; and it is well to re- 

 member in this connection that, broadly considered, motion is an 

 attribute of every form and condition of matter, great or small, 

 simple or combined, inorganic or organized. 



All forces are now regarded as modes of motion, and, since the 

 abandonment, some fifty years ago, of the theory of a vital es- 

 sence or principle, — which had itself superseded an earlier doc- 

 trine of a vital entity or substance, — science has become accus- 

 tomed to correlating the vital forces with the physical and the 

 chemical, and to looking upon all phenomena as different mani- 

 festations of a common activity, varying only in intensity and 

 range. 



This is, after all, merely a return to a method which has pre- 

 vailed at often-recurring periods, — the method of reducing all 

 scientific facts to a common denominator. No phase of philoso- 

 phical thought is more persistent than this tendency to find a fun- 

 damental unity underlying all diversity, — to clear away perplex- 

 ing mysteries by dift'using them through a universal solvent. Thus 

 biology has had to pass several times through a period in which 

 the best intellects and the most serious workers were devoted to 

 a search for an elixir of life, — something which should embody 

 the principle of creative power. These endeavors, however, like 

 the efforts of the alchemists of old, have always ended in philo- 

 sophical abstractions rather than in a concrete result upon which 

 science can lay its material hand. 



