10 SERGIUS MORGULIS 



On July 2, 1909, several worms were cut in two at about the 

 middle of the body, and in half of them the heads were likewise 

 removed. The regenerating tails were examined in both sets of 

 worms at regular jntervals, and the results are tabulated in 

 table 1. 



By the end of two weeks, July 15, the number of segments in 

 the regenerated tails of the worms with heads intact, serving as 

 the control, varied from 4 to 7, the average being 6 segments. 

 In the decapitated worms the number of regenerated segments 

 ranged from 2 to 8, while two of the worms had proliferated only 

 buds of tissue; the average for this group was 4 segments. The 

 difference in the number of regenerated segments in decapitated 

 worms and worms with heads intact was also observed in later 

 stages, as may be seen from the figures under the dates July 22 

 and 29. It is obvious, therefore, that in this experiment the extra 

 injury caused a decrease rather than an increase in the rate of 

 regeneration of the tail. 



A similar experiment was performed on July 19, the results 

 of which are given in table 2. By the close of the first week, July 

 26, the number of regenerated segments in the worms with head 

 intact varied from 2 to 5 (average 3.73), but in the decapitated 

 worms from 1 to 5 (average 3.32). Ten days and fourteen days 

 after the operation, it will be observed, both the maximum and 

 the minimum number of regenerated segments is lower in the 

 decapitated worms than in the control. Though the depressing 

 effect produced by the extra operation upon the regenerating 

 worms is not as prominent as in the previous instance, yet the 

 results are of the same kind in the two experiments. 



The experiments were repeated in a somewhat modified form 

 to find if the result could be changed by inflicting the additional 

 injury when the new tail had already started to regenerate. For 

 this purpose, a number of worms cut in two in the middle of the 

 body were separated into three groups: in the first group. A, the 

 worms were decapitated when the tails were cut off; in group B 

 the worms underwent such an operation a week after the removal 

 of the tail; and the worms of group C, with heads intact, served 

 as control for the experiment. The data are recorded in table 3. 



