MENTAL PKOCESSES 211 



own consciousness, with the result that they have 

 fallen behind in the race. 



The Transmission of Mental Variations. Mental 

 variations are transmitted from brain to brain in 

 three ways. (1) By ordinary generation. We have 

 already seen that some simple mental variations, 

 when constantly repeated so as to become uncon- 

 scious and habitual, may be recorded in the germ- 

 cells and so passed on from parent to child. But 

 physical transmission is by no means necessary for 

 handing down mental variations from one generation 

 to another. This can be done either (2) by imita- 

 tion, or (3) by communication. The latter is almost 

 entirely a human method of transmission, for it is 

 done by language either spoken or written. But we 

 see something very similar in bees and ants. 



These variations, due to imitation or to communi- 

 cation, if they are simple and constantly repeated, 

 may also become habits, and then they caa be trans- 

 mitted physically until they become instincts. 

 Usually, however, ideas transmitted by imitation or 

 communication go only to the brain, and are not 

 registered in the germ-cells. This mental trans- 

 mission, without the intervention of germ-cells, is 

 quite different from the way morphological varia- 

 tions are propagated. And now, as this mode of 

 transmission has been made easy through the in- 

 vention of the printing-press, mental variations 

 rapidly spread over the civilised world. Another 

 difference between structural and mental variations 

 is that the latter may occur in an individual at any 

 period of life, and are not solely pre-natal. And 



