USE OF THE MICROSCOPE IN ZOOLOGY. 



1 he little creatures called Stentors are very interest- 

 ing to study. Each one looks like a miniature 

 green trumpet, and is visible to the unassisted eye. 

 Look carefully at the engraving : you notice that 

 the goblet-shaped mouth is sur- 

 rounded with a circle of hairs ; these 

 are called cilia, from the Latin word 

 meaning eyelashes, a designation 

 appropriate enough. There are 

 many curious forms of these ciliated 

 protozoa, and it will be a source of 

 much pleasure to you to make their 

 acquaintance from time to time. 

 The whole body of the stew tor is, as 

 you observe, covered with cilia 

 organs which play a very useful and 

 prominent part in these creatures' 

 lives. They serve both for the pur- 

 poses of progression for by these 

 numerous hairs the animalcules row 

 themselves about with wonderful 

 rapidity and also, when arranged 

 in a circlet round the mouth, for 

 obtaining food. The constant lash- 

 ing of these cilia produces currents of water, which 

 convey to the animalcule particles of food, whether 

 of an animal or vegetable nature. These Stentors are 

 of various colours it is supposed there are many 

 species of the genus ; five or six have been described 

 either white, black, blue, or green; and like their 

 relations, the Ophrydia, are capable of assuming 

 various forms. They increase, like numerous othei' 

 forms of low animal life, by self-division. Such split- 

 ting may take place either longitudinally or obliquely, 

 and each part may form a perfect animal. You will 

 often witness animalcules in the act of separating into 



Fig. 16. Stentor. 



