220 ESSENTIALS OF BIOLOGY 



is assumed by Butler, but the " knowledge *' has the above 

 qualifications. The ovum (which is, in all respects, an organism) 

 has unconscious memory of the development of the animal of 

 which it was a part, and of the development of the parent of that 

 animal and so on indefinitely. Why should it not have such 

 unconscious memory ? It is organically continuous, in the most 

 literal sense, with all those past generations. We recognize 

 instincts, which are simply inherited but unconscious knowledge 

 of, or ability to perform, complex tectonic operations. We 

 recognize inherited or ancestral experience. Between these latter 

 conceptions and that of the unconscious tectonic knowledge of 

 the ovum and embryo there seems to be little essential difference. 

 The ovum, then, develops in the specific manner that it does 

 because a very long series of individuals, with which it was 

 organically continuous in time, have developed in this specific 

 manner and the practical knowledge, or ability to perform the 

 embryogeny is much the same thing as, for instance, the know- 

 ledge that a bird has of assembling natural materials the first time 

 that it builds a nest — this nest-building being, of course, only 

 the completion of the development of the sexually mature animal. 

 A hahit has become established in the course of the innumerable 

 individual developments in a race and the recurrence of specific 

 embryogenies expresses this habit. The habit has its basis in 

 the *' unconscious memories " of the individuals of the race, that 

 * is, in the retention, in some w^ay, of past experiences in a psychic 

 substratum : obviously one may not attempt to be more exact 

 than this. 



Why ? For the mnemic hypotheses, in its most exact formula- 

 tion by Semon only reintroduces confusion by its attempt at 

 exactness sought through a physical substratum. In these 

 formulations experiences that involve reception and response are 

 regarded as establishing " engrams," which are actual impressions 

 on, or are physical-chemical modifications of the nerve, germ and 

 somatic cells. All the confusion that results from the attempt 

 to make the developmental organization a physical agency then 

 again attaches to the hypothesis. And Bergson's analyses of the 

 mental and physical phenomena of aphasias does not seem to 

 leave any doubt that memories (images) cannot be in the material- 

 energetic brain. What a cerebral lesion does is, not to destroy 

 a memory-image, but to prevent that image from influencing 



