112 AQUATIC MICROSCOPY FOR BEGINNERS. 



ing both- plants and animals. Diatoms, Desmids, Infu- 

 soria (Chapter V.), Rotifers (Chapter VIII.), almost 

 any living things small enough to be seized, are accepta- 

 ble. When a desirable morsel is found, the end of the 

 pseudopodium touching it usually expands, and a wave 

 of the body substance flows along it until the object is 

 surrounded, like an island of food in a sea of proto- 

 plasm. The whole broadened pseudopodium is then 

 withdrawn into the body, carrying the food with it; or 

 if the captured object is unusually large, or if it strug- 

 gles a good deal, several pseudopodia may come to the 

 ■assistance of the first, or a great wave-like out-flow 

 from the body may envelop both pseudopodia and food. 



These peculiar animals have no distinct mouth and 

 no distinct stomach. The mouth in the shelless ones 

 is formed at any point on the surface wherever the 

 creature chooses to open itself and take in the food- 

 particle; and the stomach is in any part of the internal 

 substance; the food is digested wherever it may happen 

 to enter and remain. They have no eyes, yet they 

 seern to direct their course and avoid unpleasant or in- 

 jurious obstacles. They have no nerves, yet when dis- 

 turbed they contract into a small ball-like mass, or 

 withdraw themselves into their shell. They also ap- 

 pear to feel some sort of sensation of hunger, for they 

 are often seen to take food, and they select what they 

 like. 



They are numerous and common. They are to be 

 found in any shallow pond, or pool, or body of still 

 water. They glide among aquatic plants and Algas, 

 especially on the lower surface of water-lily leaves, and 

 among Myriophyllum and Ceratophyllum. Sphagnum 

 moss is sure to contain them in abundance, as has al- 



