224 University of California Puhlications in Anatomy [^oi^- 2 



static conditions would be comparable to a single picture of a moving 

 film which is, in reality, nothing more than a brief scene of a long 

 process. A ''perfect adaptation" of living beings to their special 

 environments can, therefore, be accepted in a restricted sense only. 

 Furthermore, the surrounding "world" of a given species is equally 

 unstable. Other factors forming other different "worlds" intrude 

 incessantly into it, however difficult this may be to detect. Also the 

 "worlds" of different animal species overlap each other. A steady 

 readjustment of individuals and species to new factors is therefore a 

 permanent requirement of life. The success of this readjustment will 

 greatly, though by no means exclusively, depend on the efficiency of 

 their receptor organs and the conductor and other nervous mechanisms, 

 and on more perfect and adequate utilization of stimuli. The better 

 an individual is informed about the happenings in its environment, 

 the better chances it has — caeteris paribus — to survive and to preserve 

 its species. 



The efficiency of an afferent system and of its receptor mechanisms, 

 will be higher if a more adequate, a more "true," or a more "objec- 

 tive" picture or information about the environment is received. It 

 will be of unsurpassed value if the subjective impression in all details 

 closely corresponds to the external stimuli, that is, to the external 

 objects, if the picture reproduced within the "internal world" of the 

 individual, in the first place in its central organ, is in some sense a 

 mirror image. This can be achieved only if the internal impression 

 contains constituents of stimuli of as many external factors as possible 

 and these in as faithful, mutual relation as exist in the "external 

 world" or in the objects.^ The efficiency of various afferent systems 

 and of the central organ will, therefore, depend not only on the action 

 of the neuroplasm, on its sensitiveness or susceptibility to stimuli, on 

 the speed of their transmission and so forth, and thus on the radius of 

 the action of the corresponding sense organ, but to a high degree on 

 their ability to "spatially" analyze differently composed external 

 stimuli or sets of these. And it is this latter ability to discriminate 

 small stimuli and to utilize their "spatial" or "local" qualities on 

 which the "faithfulness" or "trueness" of the internally evoked 

 impressions, pictures, or images of the external objects ultimately 

 is based. 



1 We may completely disregard here the * ' thing-in-itself ' ' of the philosophers 

 and face the world of "practical realities." 



