INFUSORIA. 137 



knowledge of tlieir existence, and of the curious plicnomcna 

 they present: yet even the best instruments afford us but 

 little insight into their real organization and physical condi- 

 tions. On this account it is extremely diflicult to assi^rQ 

 their true place in the scale of animals. By most systema- 

 tic writers they have been regarded as occupying the very 

 lowest rank in the series, and as exemplifying the simplest 

 of all possible conditions to which animal life can ])e re- 

 duced. Monads, which are the smallest of visible animal- 

 cules have been spoken of as constituting *Uhe ultimate 

 term of animality;" and some writers have even expressed 

 doubts whether they really belong to the animal kingdom, 

 and whether they should not rather be considered as the ele- 

 mentary molecules of organic beings, separated from each 

 other by the effects of chemical decomposition, and retain- 

 ing the power of spontaneous, but irregular and indetermi- 

 nate motion. It was conceived that all material particles 

 belong to the one or the other of two classes; the first, 

 wholly inert and insusceptible of being organized; the se- 

 cond, endowed with a principle of organic aptitude, or ca- 

 pability of uniting into living masses, and constituting, there- 

 fore, the essential elements of all organization. According 

 ■ to this view, all vegetables or animals in existence would be 

 mere aggregations of infusory animalcules, which gradually 

 accumulate by continual additions to their numbers, de- 

 rived from organic matter in the food: so that the body of 

 man himself would be nothing more than a vast consreca- 

 tion of monads! 



This bold and fanciful hypothesis, devised by Buffon, 

 and recommended by its seductive appearance of simplicity, 

 as well as by the glowing style and brilliant imagination of 

 its author, has had many zealous partisans. The new world, 

 which was disclosed to the wondering eyes of naturalists by 

 the microscope, abounding in objects and in phenomena of 

 which no conception could have been formed previously to 

 the invention of that instrument, was peculiarly calculated 

 to excite curiosity, and to inspire the hope of its revealing 

 the secret of the living principle in the arrangement of the 



Vol. I. IS . ■ 



