igo TRANSMISSION OF ACQUIRED CHARACTERS 



cation, become accustomed to the salt, causing it to produce a 

 generation so different from the preceding." 



Misunderstanding YIII Failure to distinguish between the 

 possible inheritance of a particular modification and the possible 

 inheritance of indirect results of that modification, or of changes 

 correlated with it. At first sight this seems hair-splitting, but it 

 is a crucial point. Through his vigorous exercise the blacksmith 

 develops a muscular arm worthy of admiration ; the shoemaker 

 acquires skeletal and muscular peculiarities less admirable. There 

 are many permanent and profound modifications associated with 

 particular occupations. Are we to believe, it is asked, that 

 the occupation of the parents has no influence on the offspring ? 

 Are we to believe, it is asked, that the children of soldier, sailor, 

 tinker, tailor, are in no way affected by the parental functions ? 



It would be interesting to have precise data in regard to 

 this, but it is generally admitted that when parents have healthful 

 occupations their offspring are likely to be more vigorous. 

 The matter is complicated by the difficulty of estimating how 

 much is due to good nurture before and after birth. It is not 

 unlikely, too, that some profound parental modifications may 

 influence the general constitution, may even affect the germ- 

 cells, and may thus have results in the offspring. But unless 

 the offspring show peculiarities in the same direction as the 

 original modifications, we have no data bearing precisely on 

 the question at issue. 



A belief in the inheritance of modifications was perhaps 

 expressed in the old proverb, " The fathers have eaten sour 

 grapes, and the children's teeth are set on edge " a proverb 

 which Ezekiel with such solemnity said was not any more 

 to be used in Israel. Now if " setting on edge " was a structural 

 modification, and if the children's teeth were " set on edge " 

 as their fathers' had been before them, there would be a pre- 

 sumption in favour of the transmission of this acquired character, 

 though it would be still necessary to inquire carefully whether 



