WHAT WE MIGHT EXPECT. 183 



to revert to an earlier impregnation. Mr. Darwin's 

 " Provisional Theory of Pangenesis " seemed to afford a 

 satisfactory explanation of this; but the connection 

 with memory was not immediately apparent. I think 

 it likely, however, that this difficulty will vanish on 

 further consideration, so I will not do more than call 

 attention to it here. 



The instincts of certain neuter insects hardly bear 

 upon reversion, but will be dealt with at some length 

 in Chapter XII. 



V. We should expect to find, as was insisted on in the 

 preceding section in reference to the sterility of hybrids, 

 that it required many, or at any rate several, genera- 

 tions of changed habits before a sufficiently deep im- 

 pression could be made upon the living being (who must 

 be regarded always as one person in his whole line of 

 ascent or descent) for it to be unconsciously remem- 

 bered by him, when making himself anew in any suc- 

 ceeding generation, and thus to make him modify his 

 method of procedure during his next embryological 

 development. Nevertheless, we should expect to find 

 that sometimes a very deep single impression made 

 upon a living organism, should be remembered by it, 

 even when it is next in an embryonic condition. 



That this is so, we find from Mr. Darwin, who writes 

 ("Plants and Animals under Domestication," vol. ii. 

 p. 57, ed. 1875) — " There is ample evidence that the effect 

 of mutilations and of accidents, especially, or perhaps 

 exclusively, when followed by disease" (which would 

 certainly intensify the impression made), " are occasion- 

 ally inherited. There can be no doubt that the evil 



