THE LOWER INVERTEBRATES 



571 



in respect to these different modalities but that, on the other hand, 

 they may be additive in their effect. Whether the reaction is positive 

 or negative there is no evidence that the response is associated with 

 subjective awareness ; and although a temporary process of condition- 

 ing may exist due to the cumulative effects of previous stimuli/ there 

 is little evidence of any true capacity for learning. Soest (1937), for 

 example, claimed that an association with electric shocks could 

 condition an avoidance of light in Paramoecium, but this behaviour 

 may well have been determined by the accumulation of metabolites 

 (Dembowski, 1950). It would therefore seem that apart from responses 

 which are explicable on a purely physico-chemical basis, we have no 

 knowledge of " vision " in the sense of perceptual awareness in this 

 phylum (see Wichterman, 1953). 



CCELENTERATA. Among Coelenterates there is more evidence for 

 assuming the existence of a lowly organization of some aspects of 

 conduct on a reflex level as well as the presence of associated 

 memory. The spontaneous movements exhibited by several species 

 either of swimming or " stepping " whether the environment is changed 

 or remains constant, are obviously the result of controlled activation 

 and inhibition - ; the same tyj^Q of conduct is seen in the daily rhythms 

 in the activity of sea-anemones and jelly-fish, such as those determined 

 by tidal changes, which may persist for some considerable time after 

 the stimulus has been artificially removed.^ That purposive reactions 

 with memory associations also exist is suggested by such types of 

 behaviour as the assumption by the anemone, Actinia, of the same 

 position in an artificial aquarium as it occupied in its natural rock 

 (van der Ghinst, 1906 ; Bohn, 1908), the apparent intelligence of the 

 anemone, AntJioloba, in climbing on the back of a crab (Brunelli, 1910), 

 or the rejection of unsuitable food after several trials by such anemones 

 as Actinia. Tealia and Cribrina (Fleure and Walton, 1907 ; Gee, 1913 ; 

 and others). In spite of these activities, however, so far as we know, 

 the phototactic reactions of this group are completely automatic and 

 fixed, and indeed have been found to remain unchanged after two 

 generations have been exposed to abnormal lighting conditions (Ewer, 

 1947). 



ECHixoDERMATA. In this pliylum, again, although some training 

 ability in the starfish, Asterias, is suggested by the observations of 

 Jennings (1907) on its capacity to right itself, or of Ven (1921) on its 

 ability to escape from a confined position, there is no proof of any 

 visual reaction except a rigid and unvaried phototactic resjDonse 

 without detectable evidence of subjective appreciation. 



Paramcecium 



Sea-anemone 



Jcllvfish 



Starfish 



1 p. 36. 



^ Hang (1933) in Hydra ; Batham and Pant in (19.50) in the sea-anemone, Metridium. 



^ Pieron(1909) in sea-anemones ; Horstniann (1934) in the jellyfish, Aurelia. 



