PARAMECIUM. 53 



their slender tubes. Possibly the polyp stinging 

 organs may have the same structure. 



Notwithstanding their dangerous weapons, polyps 

 are often infested with a parasite, the Trichodina 

 pediculus^ as shewn in Fig. E, page 47, and it must 

 happen that either this visitation is not disagreeable, 

 or that the Trichodina is not influenced by the 

 poison. 



As the plants in the bottles decayed, some of the 

 animalcules died off and others appeared. In one 

 bottle, containing decaying chara, Paramecia 

 abounded. The Paramecia^ of which there are 

 various species, have always been favourite objects 

 with microscopists. The Germans call them "slipper 

 animalcules," and they vary in size from 1-96"* to 

 1-1150". They are flat rounded-oblong creatures, 

 with a distinct integument or skin, "through which 

 numerous vibratile cilia pass in regular rows."f 

 They are furnished with a distinct mouth, and adult 

 specimens exhibit star-shaped contractile vesicles in 

 great perfection. 



The swarm of specimens before us belong to one 

 species, Paramecium aurelia^ the Chrysalis animal' 

 cule^ and they crowd every portion of the little 

 water-drop we have taken up, and examined with 



* The usual mode of giving dimensions is by fractions tlius 

 expressed, — 1-96" means one-ninety-sixth of an inch. 



t Micrographic Dictionary. 



