GRAFTING AND REGENERATION 



173 



of the other component. By means of a similar experiment we have 

 a way of rinding out if one component can influence regeneration 

 taking place from the other piece. Although Joest made only a few 

 observations of this sort, the results show that no such influence is 

 manifested. 



By means of grafting it is possible to keep alive small pieces of a 

 worm that would otherwise perish. For instance, pieces of a worm 



'" 



B 







FIG. 53. After Joest. A. Small ! piece of Allolobophora terrestris from posterior end grafted upon 

 anterior end of another individual. Oral end free. Four weeks after grafting eight new 

 segments formed, /i. Same fourteen days later. A new part of thirty-seven segments had 

 appeared at end of former eight segments. C. A piece of the body wall of Allolobophora 

 terrestris grafted upon the cut-end (anterior) of Lumbricus rubellui. Two months later, as 

 shown in figure, a head had grown on major component. D. Anterior and posterior ends of 

 A. terrestris united to make a " short worm." E. A piece of body wall of A. cyanea grafted 

 on side of body of Lumbricus rubellus. f. Piece of L. rubellui grafted on side of body of 

 another individual to produce a double-tailed worm. 



containing only three segments are not capable of independent exist- 

 ence, except for a short time, and even pieces of from four to eight 

 segments die in most cases. It is not possible to unite small pieces 

 of this size directly upon larger pieces, since they will die, ordi- 

 narily, as a result of the operation, but larger pieces can be united 

 and then after union has been effected, one of them may be cut off 

 near the place of union. The same result is sometimes brought 



