14 



ILLINOIS BIOLOGICAL MONOGRAPHS 



[14 



age of the regenerated material is derived from the old by migration and 

 a smaller percentage by cell division. The data unfortunately are based 

 on such a small number of individuals, especially in the case of new tissue 

 levels, that too much stress should not be laid on the differences. 



TABLE 2 

 Series 3676-3765 Over 4 millimeters removed Regeneration: 4 days 



Note 1. No. 3734 is left out in making up the averages because its specific 

 amount from six days of regeneration on is very much in excess of that of 

 any of the others. A probable explanation is that the end of the tail in this indi- 

 vidual had been removed and regeneration had just started when the present 

 operations were begun. If this is true it belongs to a longer removed length 

 than indicated and the specific rate is wrong. Besides a highly exceptional 

 individual even if not explained should be left out in determining the average 

 value. 



