41 6 The Living Plant 



kind of continuous axial thread upon which the body plasm is 

 strung at intervals like beads on a string, except that we have to 

 imagine the beads as growths from the string! On this theory 

 the germ plasm is the essential protoplasmic basis of the race, and 

 the body is simply an organ which it builds to secure its own 

 nutrition and protection. Now it is obvious that any variation 

 which originates in the germ plasm can show itself in all of the 

 succeeding germ plasm, and also in all of the bodies which grow 

 out therefrom; on the contrary, any variation, or other feature, 

 including an acquired character, which originates in the body 

 plasm, must perish with that body and cannot affect the bodies 

 which come after, unless it can go round through the germ plasm, 

 for which no mechanism is known to exist, excepting possibly 

 that mentioned in a paragraph to follow. This theory of Weis- 

 mann's explains very perfectly an evolution by natural selection 

 of innate (in-born or germ-plasmic) variations, and also supplies 

 a reason for the non-transmissibility of acquired characters. It 

 shows how children can exhibit cultured minds or large muscles 

 like their parents without inheriting the results of their parents' 

 culture or exercise, for while the results of culture or exercise are 

 confined to the body plasm, and perish when it does, the capacity 

 to develop the results depends on the constitution of the germ 

 plasm which parents and children share alike. The bodies of 

 children reseml^le the bodies of their parents, therefore, not be- 

 cause the former are derived from the latter, but because both 

 are derived from the same source. This ingenious theory of 

 Weismann's has not been confirmed by further research so far as 

 its physical basis in the two kinds of protoplasm is concerned, and 

 it never applied well to plants, which seem very clearly at times 

 to create germ plasm out of body plasm ; but I give it this much of 

 our attention because all recent research is tending to confirm the 

 correctness of its central principle, which stands perfectly when 

 expressed in this way, — that body characters are derived from 

 germinal determinants, which in turn are derived from preceding 



