Importance of Modifications 151 



of improving the human race. It therefore demands 

 very careful consideration. (1) No doubt advan- 

 tageous modifications are always useful for the in- 

 dividual who acquires them, and conversely. (£) 

 These useful modifications can be hammered on to 

 each successive generation. (3) They may perhaps 

 serve as a protective screen until, happily, similar 

 germinal variations may arise from within. (4) They 

 may have indirect effects on the health of the organ- 

 ism, so that the general vigor of the germ-cells is 

 improved, though there is not any entailment of a 

 particular feature. (5) In cases like mammals and 

 seed-bearing plants, where there is prolonged and 

 close physiological connection between the parent 

 and the offspring, before birth in the one case and 

 seed-scattering in the other, it is possible for ad- 

 vantageous changes in the parent to saturate into the 

 offspring. Thus there are some instances of the off- 

 spring sharing in a specific immunity acquired by 

 the mother. 



From the transmission of a particular modification 

 or even some slight representation of it, we must 

 distinguish changes produced in the germ-cells along 

 with changes in the body. Alcoholism in males through 

 successive generations may result in a deterioration 

 of offspring, but this probably means that the germ- 

 cells are poisoned as well as the body-cells. This is not 

 a case of the transmission of an acquired character ; 

 it is rather what Weismann called "parallel induc- 

 tion." Modifications induced by X-rays, radium, 

 poisons, serum-treatment, and so on may be asso- 



