infus6Ria. 13S 



currents contain the food which the Infusorium cannot 

 go to seek as the free-swimming kinds can do, for 

 the loricse-building animals are almost as permanently 

 fastened to their ' loricae as is a snail to its shell. 

 Sometimes the Infusorium will leave its lorica when 

 the water has lost most of its oxygen, and the poor 

 thing is nearly smothered, but it leaves only to die. 

 Yet it generally prefers to die at home, for when the 

 time comes the little creature retires to the bottom of 

 the • lorica, contracts into a heap, and quietly goes to 

 pieces. 



There are also some Infusoria that form loricae and 

 are still free-swimming, carrying the house about with 

 them. They likewise retire to the rear when fright- 

 ened, and some even carry a little piece of hard sub- 

 stance on the front of the body with which they plug 

 up the entrance, and so make all secure. 



There are still others that form a stem with branches 

 like the trunk and limbs of miniature trees, the 

 colorless animals being fastened to the ends like so 

 many leaves. In some of these the animals can con- 

 tract themselves' into little balls when frightened; in 

 others the branches contract into coils and withdraw 

 the animals from harm; in still others the whole tree- 

 like colony; stem, branches and animals, contract and 

 huddle down against the plant to which the stem is 

 attached. And in still others, the Vorticilla, there is 

 but a single stem with a single bell-shaped body on 

 the end, but the stem contracts into close spirals and 

 suddenly draws the animal down. When the danger is 

 past, the stem slowly uncoils, the branches spread 

 themselves, the animals expand, and all is as before. 

 Indeed, the variety of form and habit in the Infusoria 

 is exceedingly great. 



