i6o LEISURE-TIME STUDIES. 



the higher fields of life, the contest regarding spontaneous 

 generation was, as the sequel will show, destined to be 

 fought again in the arena of lower and microscopic existence. 



The experimenters who first appeared, a century after 

 the Florentine philosopher, to work out the subject of ani- 

 malcular origin, were Needham and Buffon. With the name 

 of the latter every one must be familiar, as that of a na- 

 turalist who added largely to the zoological and botanical 

 knowledge of his time; whilst the former, an English ex- 

 perimenter, comparatively unknown outside the records of 

 scientific discovery, was assisted by Buffon in much of his 

 work. Needham himself speaks with some surprise of the 

 almost universal acceptance with which Redi's views had 

 met, and, as we shall presently note, found cause to disagree 

 most strongly with the opinions of the latter. Writing at 

 the middle of the eighteenth century, Needham says : 

 " Modern naturalists unanimously agree in holding it as a 

 certain fact that every plant originates from a specific seed, 

 every animal from an egg, or from some analogous thing, 

 pre-existing in the plant or in the animal of the same species 

 which has produced it." And as regards the origin of the 

 animalcules themselves, another sentence, translated from 

 Needham's " Observations," written in French, will serve to 

 show the ideas entertained by his contemporaries on this 

 head. "Naturalists have generally believed," says Need- 

 ham, " that microscopic animals were generated from eggs 

 carried by the air or deposited in still waters by insects." 



The population of stagnant waters and putrescent fluids 

 was thus supposed to be produced by the development 

 therein of the minute eggs or germs of the animalcules ; and 

 Needham, with a laudable desire to place his own belief on 

 a scientific and experimental basis, began to experiment on 

 fluids in which the lower and minute forms of life were 

 likely to be developed. Provided with a fluid which pre- 

 vious experience had proved to be capable of containing 

 and supporting animalcules, Needham adopted exactly the 

 principles of Redi, exhibited in the experiment on the de- 



