22 DROPS OF WATER. 



of heat also. The same naturalist says, that the 

 Polygastrica will bear the temperature gradually 

 raised to 120 of Fahrenheit, and some even 

 to 200, but if raised suddenly they die at 140. 

 Now, if we consider that water raised to 212 is 

 boiling, we shall be as much astonished at their 

 powers of enduring heat, as cold. Sir James 

 Ross, in his Antarctic Expedition, found upwards 

 of seventy species of Polygastrica with lories, or 

 siliceous shells, in fragments of ice. 



It will, therefore, be seen, that animalcules are 

 obtainable at all seasons, and in every place 

 where there are ponds or pools of water ; or 

 they may be procured from water-butts, or by 

 placing leaves, hay, or almost any vegetable sub- 

 stance in a little water, which lias been previ- 



