10 THE PRINCIPLES OF HEREDITY 



from the soma, and that as the soma undergoes modification 

 so do the packets of gemmules in the germ-cells undergo 

 change by the incursion of fresh gemmules. Of course, how- 

 ever, even were the transmission of acquirements demon- 

 strated, it would not necessarily follow that it is achieved by 

 means of germinal elements from the soma. Other means 

 of transmission are conceivable. On the other hand, were 

 the contrary demonstrated, all such theories would lose their 

 only justification. 



17. It must be noted that a character acquired by the 

 parent can never be inherited as an acquirement by the off- 

 spring. For were an acquirement transmitted it would arise 

 in the second individual in consequence of influences acting 

 on the germ-plasm, whence he springs, not on his soma. 

 The child would be lorn different from what the parent was 

 born. 1 It would make a different start in life. The modifi- 

 cation of the parent would therefore reappear in the child as 

 a new inborn trait a variation. Similarly since a variation 

 implies a difference from the parent it can never be inherited 

 as such by the offspring. If, then, the hypothesis we have 

 under consideration be true, the modifications of the parent 

 tend to be transmuted into variations in the child, and into 

 ordinarily inborn traits in the grandchild. The theory that 

 acquirements are transmissible to offspring is therefore 

 nothing other than one way of accounting for the occurrence 

 of variations, and ultimately of ordinary inborn traits. It will 

 be necessary to discuss this theory at length, partly for the 

 reason that, though now rejected by most students of heredity, 

 it was, until recently, universally accepted by all peoples 

 during all ages as affording a sufficient explanation of such 

 racial changes as were not attributed to miracle, partly 

 because it is still accepted by the majority of human beings, 

 and partly because it will enable us to gather clearer ideas 

 of what most serious students of the subject regard as a truer 



1 The word "born" is used here to avoid circumlocution, just as the 

 term " inborn" is similarly used. But of course, as already indicated, 

 birth does not divide the inborn from the acquired. The embryo and 

 the foetus may acquire characters (e. g. the effects of disease or the 

 muscular development which probably follows intrauterine movements) 

 just as well as the infant or adult. Again, when a child is spoken of as 

 born different from the parent it is not necessarily meant that the 

 difference lies in visible characters. It may consist in a capacity to 

 develop differently from what the parent developed, or to react differ- 

 ently to similar stimuli. Were an acquired character inherited the 

 child would differ from the parent in that it possessed the capacity to 

 develop that trait in the absence of the force that caused the parent to 

 develop it. 



