[ 597 1 



ANIMALCULES*. 



THESE animals are very simple in their form, and 

 generally invisible without a magnifying power. — ■ 

 They are chiefly found in infusions of animal and 

 vegetable substances. 



Their multiplication long occupied the attention 

 and eluded the researches of philosophers. The dis- 

 covery, however, a few years back, that some of the 

 larger animals increased by a spontaneous division, 

 gave rise to the conjecture that these microscopic 

 animalcules might multiply their numbers in a si- 

 milar manner. This conjecture was communicated 

 to M. de Saussure in a letter from Bonnet, who re- 

 ceived an answer from Genoa in September 1769, to 

 the following purport : 



" What you propose as a doubt (says M. de 

 Saussure) I have verified by incontestable experi- 

 ments, namely, that infusion animalcules multiply 

 by continued divisions and subdivisions. Those 

 roundish or oval animalcules that have no beak or 

 hook on the fore-part of their bodies, divide trans- 

 versely. A kind of stricture or strangulation begins 

 about the middle of the body, which gradually in- 

 creases, till the two parts adhere by a small thread 

 only. Then both parts make repeated efforts, till 



* The Animalcules, or Infusoria, constitute the last of thr 

 Linncan Orders of Worms. 



