OUR NATURAL INHERITANCE 61 



characters or Mendelian characters behave as if they 

 were discrete entities which can be shufHed about and 

 distributed to the offspring in some degree independently 

 of one another and which can be reunited in new com- 

 binations. They must be represented in the germ- 

 cell by ' factors ' or * determinants ' or organisational 

 peculiarities of some sort. One of the latest names for 

 a hereditary ' factor ' is ' gene.' 



(c) The third very important idea that has been 

 brought into prominence in modern times is that bodily 

 modifications — dints and imprints — acquired by an 

 individual as the direct result of peculiarities in nurture 

 are not readily transmissible, if at all, and, in any case, 

 are not usually transmitted. Every care must be taken 

 to avoid dogmatism, but it is certain that individually 

 acquired modifications (in the technical sense) are not 

 commonly transmitted to any observable extent. We 

 must go further and say that it is exceedingly difficult 

 to find incontrovertible evidence showing that they 

 may be even occasionally transmitted. 



It will be necessary to return to the subject when 

 we discuss ' Nurture' ; in the meantime the dominant 

 scientific opinion may be stated, that in our discussions 

 and reflections on heredity we are not warranted in 

 taking for granted, as has often been done in the past, 

 that modifications individually acquired by an organism 

 can be handed on to its offspring, either as such or 

 in any representative degree. An individual living 

 creature often exhibits modifications directly due to 

 some peculiarity or change in surroundings, food, 



