62 THE PSYCHIC LIFE 



Amoebae; for these organisms, the condition necessary 

 to the perception of a solid particle is contact with it. 

 A step forward has been effected in those organisms 

 that are able to perceive external objects by contact 

 from a distance, as is observed for instance in the 

 AetinophryS) which perceives all bodies that chance to 

 touch its long filamentous pseudopods; yet, in this in- 

 stance, the pseudopod merely acts the part of an ex- 

 tended tactile organ. The vibratile cilia, and still 

 more the long lash of the Mastigophores, enable the 

 animal to discern the presence of contiguous particles 

 at a certain distance from its body, by the pressure 

 exerted upon their appendages. It is not known 

 whether there are many animalcula that perceive the 

 presence of nutriment from a distance and without 

 coming in direct contact with it; it appears, however, 

 that this is the case with the Didinium which shatters 

 its prey from a distance and without touching it. 



2. Choice. We have seen that Micro-organisms do 

 not absorb indiscriminately every solid particle they 

 meet. They exercise a choice. Among the lower spe- 

 cies, the choice is in the lowest degree rudimentary; 

 the organism restricts itself to a discrimination of 

 mineral particles, sand for example, from organic sub- 

 stances; it rejects the former and absorbs the latter. 

 Among the higher animalcula the choice is more in- 

 telligent. There are Infusoria that feed only upon 

 plants and animals. There are also those which feed 

 exclusively upon one species. 



This exercise of choice is one of the most incom- 

 prehensible of phenomena; it is exceedingly difficult 

 to explain it without resort to anthropomorphism. If 

 we hold to what observation directly teaches us, the 

 choice may be said to consist in the following acts: 



