IXFUSOBIAL ANIMALCULES. 29 



however, may be easily overlooked ; for they merely 

 resemble, even under a power of 250 diameters, scintilla- 

 tions, or the vibrations of cilia, among the vegetable 

 matter. But, when carefully examined under a deeper 

 power, they will appear like so many small short rods, 

 each rod, or chain, having a distinct movement of its 

 own. 



SECTION VI. Effects of Temperature on Infusoria, 



As vitality in these creatures is not destroyed by the 

 ordinary cold of winter, most of the common Polygastrica 

 may be found at that season in ponds under the ice. The 

 Vorticella microstoma will live after being exposed to 

 8 of Fah., and the ice gradually thawed ; although the 

 number in this case may not exceed one in a hundred. 

 Below this temperature they will not survive. The same 

 may be said of the Monas termo and spirillum, the 

 Paramecium aurelium, Cyclidium glaucoma, Glaucoma 

 scintillans, and Kolpoda cucullus. When Infusoria are 

 destroyed by the cold, no rupture or injury will be appa- 

 rent on their bodies, excepting with the Chilodon cucullus, 

 and some few others, which, under these circumstances, 

 will often become dissipated. The Stentor polymorphus 

 and mulleri will not live many hours in a temperature 

 of 9 Fah. ; and arborescent Vorticella, when subjected to 

 that degree of cold, fall from the stalks and die. 



The Rotatorial animalcules cannot endure so low a 

 temperature as those above named. 



When a small quantity of water, having animalcules 



