ACQUIRED CHARACTERS 161 



That these speculations have produced ahiiost no 

 effect on present biological thought is not surpris- 

 ing, for a moment's consideration will show that, at 

 best, the basis for the comparison between memory 

 and heredity rests only on a vague analogy. In each 

 case something appears and reappears. In the one 

 case, a memory of the past in the brain as we say; 

 in the other case, a repetition of a similar type of 

 behavior in successive generations. It is tacitly im- 

 plied that because memory is a familiar process to 

 us we must know more about it than about heredity. 

 The fact, however, is that memory is one of the many 

 obscure fields of human j^sychology. It is today more 

 obscure to us than is heredity itself. Are we not jus- 

 tified, therefore, in looking askance at attempts to 

 account for a phenomenon taking place in one realm 

 of observation by an appeal to another, less w^ell 

 understood? It is not an exaggeration to say that 

 some of those who have propounded memory the- 

 ories of hereditv have never been in close touch with 

 the facts of heredity and development that are fami- 

 liar to students of these subjects. Our present knowl- 

 edge of the relations of parent to offspring is so 

 different from anything ever imagined by the mem- 

 ory advocates, that their speculations a^^pear to the 

 zoologist as crude as they are often grotesque. 



During the last quarter of the last century, one of 

 the most important branches of biology came to frui- 

 tion. The microscopic study of cells and eggs and 



