452 T. H. MORGAN. 



The results from Tables VI and VII show that one cannot 

 say definitely, ''here the power of regeneration ends." The 

 figures show that some worms regenerate where others fail to 

 do so. It may be that the possibilities are different for different 

 worms, or that at the time of operation certain worms were in 

 better condition than others, or the external conditions (bac- 

 teria, &c.) may have been different in different cases. 



The tables show that posterior to the twelfth segment the 

 power of regeneration rapidly decreases. Worms that have 

 lost more segments than this number may live for some time, 

 and heal up the wound, or even regenerate imperfectly. But 

 sooner or later the majority of these die. Occasionally re- 

 markable exceptions are found. In Table VI the fifth record 

 shows that a worm that had lost nineteen segments regenerated 

 four or five new ones, and in the next tables more remarkable 

 cases still will be recorded. 



It is a tedious operation cutting off a definite number of 

 segments from a living worm. In the three following tables 

 the number of segments cut off was not counted at the time, 

 but could be calculated with approximate certainty after re- 

 generation by the position of the vasa deferentia or segments 

 containing the seminal receptacles, or, when the amputation 

 was behind these, something like an approximation could be 

 obtained by utilising the anterior end of the clitellum, or even 

 the posterior end of the body. 



