]86 ANIMALCULA OT INFUSIONS. fi 



are likewlfe fatal to infeds, as the vacuum of an 

 air pump. 



The motions of animalcula concur in proving 

 their animality. They are not the fame in all, 

 but different, and produced by different means 

 pecuUar to each fpecies. Many move in infufions 

 only by undulating the body, as eels do in fwim- 

 ming. That undulation is not fmiilar in every 

 one ; for fome form a few flight curvatures, o- 

 thers deep and numerous. The figure is formed 

 in a moment by fome, by others flowly and gra- 

 dually. The arms, points, and fibrils, proceed- 

 ing from the extremity of the body, are inflru- 

 ments for many animalcula to fwim : fome are 

 long, fome Ihort, fome ftrike the water often, 

 others feldom, and the refl with various degrees 

 of velocity. There are animalcula whofe motion 

 is very languid, and there are fome that move 

 mofl rapidly. Some move at intervals ; the mo- 

 tion of others is perpetual : they never feem to 

 reft. I have feen one fpecies whofe pofterior fibres, 

 difengaged and feparated far afunder, folding to- 

 gether in an inftant, darted the animal to a confi- 

 derable diftance, like an arrow from a bow. The 

 courfe of feveral fpecies never deviates from a 

 flraight line ; others continually pitch up and 

 down like a veffel at fea. Some whirl like tops 

 or balls on themfelves, without moving from the 

 fpot 3 while others have a progreffion during this- 



rotatory 



