134: MICROSCOPY FOR BEGINNERS. 



the microscopist who may be seeking it. But they are 

 not formed entirely by accident. They are built chiefly 

 of those little particles brought to the animal by the 

 currents produced by the organs it has for that purpose. 

 These currents contain the food which the Infusorium 

 cannot go to seek as the free-swimming kinds can do, 

 for the loricas building animals are almost as perma- 

 nently fastened to their loricse 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, and it leaves only to die. But 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 that form loricse and are still 

 free - swimming, carrying the house about with them. 

 They also retire to the rear when frightened, and some 

 even have a little piece of hard substance on the front 

 of the body with which they plug up the entrance, and 

 so make all secure. 



There are others that form a stem and 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 contract themselves 

 into little balls when frightened ; in others the branches 

 contract into coils and pull the animals away from harm ; 

 in still others the whole tree-like colony, stem, branches, 

 and animals, contract and pull themselves down against 

 the plant to which the stem is attached. And in still 



