PSYCHIC GRADATIONS. 123 



plastidules or micella, of which its living cell-body is 

 constructed. As regards the extraordinary perfor- 

 mances of unconscious memory in these unicellular 

 protists, nothing could be more instructive than the 

 infinitely varied and regular formation of their 

 defensive apparatus, their shells and skeletons ; in 

 particular, the diatomes and cosmaria among the 

 protophytes, and the radiolaria and thalamophora 

 among the protozoa, afford an abundance of most 

 interesting illustrations. In many thousand species 

 of these protists the specific form which is inherited 

 is relatively constant, and proves the fidelity of their 

 unconscious cellular memory. 



II. Histionic memory. — Equally interesting examples 

 of the second stage of memory, the unconscious memory 

 of tissues, are found in the heredity of the individual 

 organs of plants and the lower, nerveless animals 

 (sponges, etc.). This second stage seems to be a 

 reproduction of the histionic presentations, that associa- 

 tion of cellular presentations which sets in with the 

 formation of ccenobia in the social protists. 



III. — In the same way we must regard the third 

 stage, the unconscious memory of those animals 

 which have a nervous system, as a reproduction of 

 the corresponding " unconscious presentations " which 

 are stored up in certain ganglionic cells. In most 

 of the lower animals all memory is unconscious. 

 Moreover, even in man and the higher animals, to 

 whom we must ascribe consciousness, the daily acts 

 of unconscious memory are much more numerous 

 and varied than those of the conscious faculty ; we 

 shall easily convince ourselves of that if we make an 

 impartial study of a thousand unconscious acts we 

 perform daily out of habit, and without thinking of 



