54 THE PSYCHIC LIFE 



The prehension of food by the Didinium exhibits 

 interesting aspects, which have not as yet been ob- 

 served in any other Infusory. M. Balbiani, in his 

 first observations, had often been surprised at seeing 

 animalcula that the Didinium had passed by without 

 touching, suddenly stop as if violently paralyzed; 

 whereupon our carnivorous specimen straightway ap- 

 proached and seized them with seeming facility. 

 More careful examination of the Didinium's actions 

 soon furnished the key to this enigma. If, while 

 swiftly turning in the water, the Didinium happens 

 into the neighborhood of an animalculum, say a Para- 

 mecium, which it is going to capture, it begins by 

 casting at it a quantity of bacillary corpuscules which 

 constitute its pharyngeal armature. The Parmecium 

 immediately stops swimming, and shows no other 

 sign of vitality than feebly to beat the water with its 

 vibratile cilia; on every side of it the darts lie scat- 

 tered that were used to strike it. Its enemy then ap- 

 proaches and quickly thrusts forth from its mouth an 

 organ shaped like a tongue, relatively long and re- 

 sembling a transparent cylindrical rod; the free, ex- 

 tended extremity of this rod it fastens upon some part 

 of the Paramecium's body. The latter is then grad- 

 ually brought near by the recession of this tongue- 

 shaped organ towards the buccal aperture of the 

 Didinium, which opens wide, assuming the shape of 

 a vast funnel in which the prey is swallowed up.* 



Up to this point we have paid little attention to 

 movements of defence and of flight. Upon this sub- 

 ject a few words will suffice. When vorticels are 

 alarmed, they are seen to contract forcibly their pedi- 



* Archives de zoologie experimental, 1873, Vol. II, p. 363. Observations sur 

 le Didinium nasutum, by E. G. Balbiani. 



