88 



Papers from the Marine Biological Laboratory at Tortugas. 



gives the difference in the average regeneration between the fourteenth and 

 twenty-fourth days. Table 2 shows that in the concentrated solutions, 

 105 to 125 per cent, there was no additional regeneration; in fact, three out 

 of four solutions showed a decrease and in one solution the increase was 

 only 0.63 mm. In all the dilute solutions, however, there was an increase, 

 in sea-water 3.03 mm., in 95 per cent solution 2.96 mm., 90 per cent solution 

 2.63 mm., etc. It should be noted that the increment was unequal, a greater 

 relative and absolute increase occurring not in the optimum solutions, but 

 in 75, 70, and 65 per cent solutions. 



Table 2. Extent of regeneration during the second period, i. e., between the 

 fourteenth and twenty-fourth days after amputation. 



In the third set of observations, made on the thirtieth day, the measure- 

 ments were not taken from the amputated level, for at this stage of develop- 

 ment it was difficult to tell with exactness where that level was. The last 

 measurements were made from the end of the knob-like mass at the distal 



Fig. 2. Thin line 

 represents regen- 

 erating after 14 

 days; thick line 

 after 24 days; 

 broken line after 

 30 days . 2 



end of the amputated arms, and the measurements in table i, therefore, 

 appear smaller than the corresponding measurements for the preceding 

 periods. 



The character of the curve is essentially the same as the 24-day curve, 

 differing from it in the same way that it differs from the 14-day curve. It 



