212 A Strange Place for Rotifers . 



floating dust. The consequence was that in a week or two 

 much more organic matter was present than had been in the 

 hygrometer vessel, but this did not lead to increase in the 

 rotifers, which on the contrary decreased, although some new 

 animalcules (trachelitis, etc.), made their appearance, and one 

 very delicate round, empty test — probably of a difflugia — was 

 observed. This was curious on account of its being covered 

 with what appeared to be microscopic crystals of carbonate 

 of lime. 



As it cannot be supposed that clean undecayed fibres of 

 cotton were devoured as food by any members of the colony, 

 they must all have lived on the very minute quantity of other 

 organic matter present, and either in decomposition or growth. 

 The monads were probably vegetable, though possibly animal. 

 They appeared to form the food of the rotifers, and had 

 nothing noticeable to live upon. 



This accidental experiment affords an illustration of the 

 fact that very minute quantities of organic matter in decay are 

 sufficient to lay the foundation of, and for a time support, a 

 numerous infusorial colony, which may include objects of com- 

 paratively high organization. The wind may have carried 

 small rotifers, or their eggs, on to the cotton; or, which" is 

 more likely, one may have been imported in the cistern water 

 with which the hygrometer vessel was filled ; and, notwith- 

 standing the limited supply of food, the creature and its pro- 

 geny flourished for many weeks. 



