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; thiick 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. ;. i 



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 



