52 THE PSYCHIC LIFE 



The hunter Infusoria are frequently armed with 

 tricho cysts. Trichocysts are urtical filaments which 

 serve the animalcula provided with them to disable or 

 wound other micro-organisms. 



A large unmber of Infusoria, the Paramecia, the 

 Ophryoglena, etc., use their trichocysts as organs of 

 defense. With other species, of which we shall speak 

 more at length, the trichocysts are organs of offense. 

 They are located either in the sides of the mouth or 

 in parts adjacent thereto; this is the case with the 

 Lacrymaria, the Didinium, the Enchelys, the Lagynus, 

 the Loxophyllum, and the Amphileptus. 



These latter animalcula attack the live prey that 

 constitutes their food, in the following manner. They 

 dash upon their victim and bury the trichocysts with 

 which they are armed, into its body. The Victim is 

 immediately brought to a halt, whereupon the hunter 

 seizes it and swallows it. So, when the Lagynus Elon- 

 gatus intends to seize a victim that has fallen into its 

 vortex and has thus been drawn into the neighbor- 

 hood of its mouth, it throws itself swiftly forward. At 

 the moment of contact the hunted Infusory becomes 

 suddenly paralyzed and remains perfectly motionless. 

 This paralysis is evidently caused by the trichocysts 

 which line the aesophagus of the Lagynus and with 

 which the latter has transpierced its prey at the mo- 

 ment it came in contact by its anterior extremity.* 



In a higher stage of organization, the Microzoon 

 possessing a mouth changes its position in order to 

 intercept its prey, and give it chase. 



The Didinium Nasutum (Stein), a carnivorous In- 

 fusory and one of the most voracious of our fresh stag- 

 nant waters, operates in a more complicated manner: 



* Maupas, op. cit., p. 495. 



