136 MICROSCOPY FOR BEGINNERS. 



confined to a circle around one end, or they may be on 

 the lower surface only, or the whole body may be cov- 

 ered with them. Infusoria with cilia are more numer- 

 ous than Infusoria with flagella. They are, however, 

 not the only ciliated animals. The Eotifers are well 

 supplied, and certain small aquatic worms have the en- 

 tire body ciliated. 



Although the Infusoria are so abundant that scarcely 

 a drop from any pond or ditch can be examined with- 

 out exhibiting some, the beginner will, I fear, have trou- 

 ble in studying them, they are so lively and so small. 

 The stage must be kept in continuous motion to coun- 

 teract the motions of the Infusorium and keep it in the 

 field, so it can be seen as anything more than a whirling 

 speck, and high-powers are needed to examine it. But 

 the beginner's object will be gained if he learns to know 

 an Infusorium when he sees one, and if he learns the 

 names of some of the largest and commonest. Many 

 can be seen with a one-inch objective, but to ascertain 

 whether any special one has cilia or flagella will demand 

 a one-fifth inch or higher power lens, and without know- 

 ing this the Infusorium cannot be identified. But "it 

 is only the first step that costs." Any work or study is 

 always hardest at the beginning. When the student has 

 identified one Infusorium he will have little trouble with 

 what comes after. The attached forms will not be very 

 difficult even at the first, if a sufficient magnifying pow- 

 er is used, for since they are fastened by stem or lorica 

 to another object, they can be examined at leisure. 



