AXTMALCULE TANK. lol 



succeed much better, and not only preserve our 

 population longer, but enjoy a succession of animated 

 crops. Extensive decomposition of vegetable matter 

 kills off all but certain families, such as Paramecia, 

 who enjoy it; on the other hand, too little decom- 

 position proves fatal to some creatures, by depriving 

 them of their food, and when they have died off, 

 those who depended upon them for a living, die 

 too. Different vegetables in decomposition suit dif- 

 ferent creatures, and hay and straw in that state 

 seem to please the largest number. An animalcule 

 tank will succeed best when it contains two or 

 three kinds of grooving plants, which oxygenize the 

 air, and a moderate variety of decomposing organ- 

 isms will supply food without making the water 

 offensive. 



From these considerations it will be apparent that 

 not only the nature of the vegetation of a pond, 

 which is often changed by accidental circumstances, 

 but also the quality of the odds and ends that 

 the winds may blow into it, or which may fall 

 through the air, will do much to determine the 

 character and numbers of its inhabitants, while the 

 quantity of shade or sunshine it enjoys, will also 

 exercise an important inHuence. Hay and other 

 infusions have from the beginning of microscopic 

 investigations been employed to obtain the creatures 

 which the Germans call "Infusions thierchen," (In- 



