164 HEREDITARY CHARACTERS 



The case of malaria again serves as an example. If the 

 poison produced by the malarial parasite affected the germ 

 cells as well as the body of the parent, it is not conceivable 

 that the effect could be anything but injurious, it could 

 do the germ cells no good. In the same way, anything 

 injurious to the individual must injure the germ cells 

 also, unless they are highly resistant to the environment. 

 Favourable variations in the germplasm can only be pre- 

 served and permanent improvement in the race take place 

 if the germplasm and germ cells are highly resistant to any 

 external influences. 



The evidence bearing upon the subject shows that we 

 have no undoubted example of the transmission of an 

 acquired character. This, however, does not make it legiti- 

 mate to say that acquired characters can never be trans- 

 mitted. A general consideration of the case seems to show 

 that it is safe to conclude that acquired characters can be 

 transmitted but very rarely, if ever, and that natural selec- 

 tion must tend to eliminate variation in this direction if it 

 happens to occur in any organism. 



There does not appear, then, to be any evidence showing 

 that the environment has any effect in the production of 

 progressive variations in the germ cells. In fact, the 

 evidence seems to show that natural selection must have 

 tended towards making the germ cells or germplasm highly 

 resistant to the environment. 



It has been suggested l that, when life was near its origin, 

 there arose among the simple organisms then existing some 

 that varied from the parent organism. This result may 

 have been brought about by the action of the environ- 

 ment being different upon different portions of the organism. 

 This is of course speculation pure and simple, but as we 

 have no evidence with regard to the subject, nothing more 

 than speculation is possible. 



The conclusion arrived at with regard to variations may 

 be summarised as follows: We have the simple fact that 



1 Reid, Archdall, Principles of Heredity, 1905, p. 95. 



