710 A. “Ff. Goldfarb 
on Antedon (Przibram ’or) gave quite the contrary results. 
After the removal of the oral disc with its nerve ridges, the missing 
parts were regenerated perfectly, but when the aboral system 
within the central capsule was injured or destroyed, regeneration 
was inhibited. My own experiments consisted in cutting wedge- 
shaped pieces from the amputated ends, either on the oral or aboral 
surfaces or on the side, different arms being used for each of these 
operations. With the aboral piece a portion of the apical nerve 
together with adjacent tissues was removed; the oral piece con- 
tained the two parts of the oral nervous system together with part 
of the ambulacral system and other tissues; the lateral piece 
did not include any of the nerve tracts. In the first two instances 
regeneration of the arm was inhibited until the space had been 
almost filled in by new tissue, after which regeneration of the rest 
of the arm took place. ‘The time required for the aboral surface 
to complete itself was very brief, for the oral surface, considerably 
longer. ‘These facts may be interpreted to mean that both the 
oral and the aboral nerve ridge must be present at the amputated 
surfaces before regeneration begins. ‘The absence of either one 
prevents for a time at least the formation of a new arm. ‘That 
this is not the correct interpretation is shown by removal of nerve 
ridges only, without seriously injuring the other tissues, and by 
leaving the amputated surface otherwise complete. ‘This was 
done in a group of 80 small starfish from each of which several 
arms were amputated at the same level. By means of a broach 
or a hot needle the apical nerve ridge of at least one arm and the 
oral ridges of another were destroyed. ‘The latter method was 
found to be worthless for arms so treated invariably disintegrated 
to a more proximal level. The broach method was more satis- 
factory. The rough treatment often caused the arm to break off at 
its base, or to slough off the injured part. Such animals were dis- 
carded. In some, the saw-like action of the broche divided the 
oral surface in two, thereby destroying both layers of the oral sys- 
tem. Whatever the mode of operation the result was the same, a 
new arm was regenerated. 
In about 15 days the eye spot was discernible in the operated 
arms and in the non-operated arms. In many instances to be 
