HEREDITY, VARIATION AND DEATH 29 



of injuries, is found in higher classes of animals. Stags replace 

 lost horns, and birds at every moult replace lost feathers. If 

 we turn to plants we find the power almost unlimited : a bud is 

 formed and from it grows a shoot that bears flowers Le. practi- 

 cally a new plant. Besides this, there is a phenomenon which 

 is often spoken of as distinct from the last-mentioned, though 

 really the same. One organ of a plant will produce another 

 organ which is not properly found there. A slip is cut from 

 a willow, and when it is put into the ground it throws out roots. 

 If you look into the hollow of a decaying willow tree you will 

 find the branches sending out roots into the rotten wood, the 

 mortified parts of the tree being food to the living. All these 

 phenomena admit of one explanation, though, to strengthen the 

 case against Weismann and his germ-plasm, they have been care- 

 fully classified and distinguished till it has seemed that there are 

 a host of dragons in the path, some one of which must be capable 

 of strangling the unfortunate theory. Weismann's defence, I 

 believe, meets all these attacks, but the technicality of the terms 

 he has used and his elaboration of hypotheses have sometimes 

 produced the impression that weak points have been discovered, 

 and that there has been a complete breakdown. Stripped of 

 all technicalities, I think his answer to these objections amounts 

 to this. In the development of the animal body, after some of 

 the initial stages, in some cases from the very first, specialisation 

 of the germ-plasm takes place. Some elements are sent here, 

 others there, as they are required. Before development has 

 advanced far some of the somatic or body-cells may contain 

 germ-plasm unaltered. In some of the lower animals, such 

 as the hydra, this state of things may continue through- 

 out life. Whenever in a hydra reproductive cells are 

 formed, or in a plant flowers containing seed and pollen, 

 secondary sexual characters are added. But cells essen- 

 tially similar, in that they contain germ - plasm, exist in 

 other parts of the hydra or the plant. Thus, so far as 

 continuity is concerned, Weismann has maintained his position ; 

 as to localisation, he has had to make concessions and to 

 modify his theory. 



