iy8 TRANSMISSION OF ACQUIRED CHARACTERS 



may be a most unfortunate phrase, but it has come to have a perfectly 

 definite technical meaning and usage, which any normal person 

 can understand in a few minutes. Prof. W. K. Brooks, in his 

 Foundations of Zoology, says that he never uses the phrase " inherit- 

 ance of acquired characters " except under protest, and this may 

 be commendable restraint ; but it seems to us inconsistent with his 

 usual wisdom to go on to say, " If any assert that the dog inherits 

 anything which his ancestors did not acquire, their words seem 

 meaningless ; for, as we use words, everything which has not existed 

 from the beginning must have been acquired although one may 

 admit this without admitting that the nature of a dog is, wholly 

 or to any practical degree, the inherited effect of the environment 

 of his ancestors." But as the word " acquired " is now a technical 

 term, meaning wrought out on the body as the result of changes in 

 environmental or functional stimuli, we fail to see that, as we use 

 the words, there is anything meaningless in the first assertion, or 

 any warrant for the second. 



Summary. What forms the material basis of all inheritance, 

 in all ordinary cases of sexual reproduction among multicellular 

 organisms, is the fertilised ovum. The question under dis- 

 cussion is, physiologically stated, whether we can conceive that 

 structural changes in the body of a parent, induced by changes 

 in functional or environmental influence, can so specifically 

 affect the reproductive cells that these will, if they develop, 

 reproduce in any degree the modification acquired by the parent 

 or parents. The question under discussion, logically stated, 

 is whether there are any secure phenomena of inheritance 

 which forcibly suggest the reality of the transmission of acquired 

 characters ; or whether, if such phenomena there be, a simpler 

 interpretation may not be found. If, summing up in Galton's 

 phrase, we call environmental and functional influences " nurture/' 

 our question is seen to be the exceedingly important one, May the 

 results of peculiarities in parental " nurture" be as such trans- 

 mitted, or is it the germinal " nature" alone that constitutes the 

 inheritance ? 



