560 Charles Zeleny 
ZELENY, C.’05-2—The Relation of the Degree of Injury to the Rate of Regenera- 
tion. Journal of Experimental Zodlogy, vol. 11, no. 3. 
’°o7—The Effect of Degree of Injury, Successive Injury and Functional 
Activity upon Regeneration in the Scyhomedusan, Cassiopea xama- 
chana. Journal of Experimental Zoology, vol. v, no. 2. 
°0o8—Some Internal Factors Concerned with the Regeneration of the 
Chelz of the Gulf-weed Crab (Portunus sayi). Carnegie Institution 
of Washington. Publication no. 103. Tortugas Laboratory Re- 
ports vol. i. 
‘og—Successive Regenerations. Journal of Experimental Zodlogy. Vol. 
Vii, no. 3. 
APPENDIX 
After the manuscript of this paper was sent to press the author received an 
important paper by Stockard! dealing in part with the question of the relation 
of the degree of injury to the rate of regeneration. Stockard has performed 
experiments on the arms of the Scyphomedusan, Cassiopea xamachana and 
the arms of the brittle-stars Ophiocoma riisei and Ophiocoma echinata. He 
concludes that “‘the medusa, Cassiopea, regenerates each oral arm at a rate which 
is independent of the degree of injury when replacing either one, two, four or six 
of its arms. If, however, eight arms are amputated, each arm is regenerated at a 
rate which, after taking account of the probable error, is significantly greater than 
the regeneration rates in medusz injured to any less extent. 
“The brittle star, Ophiocoma riisei, regenerates either one, two, three, four or 
all five arms at rates which are not significantly different. In other words, there 
is no relation between the rate of the individual arms and the degree of injury in 
this species. 
“The rate of regeneration for individual arms in Ophiocoma echinata, another 
species of Ophiuran, is fastest when only a singlearm is regenerating and success- 
ively slower when two, three, four and five arms are being replaced. The rate of 
regeneration is slower the greater the extent of injury.” 
In the first case, that of Cassiopea, Stockard finds that the animals decrease in 
size during the course of the experiments, the ones with a greater number of removed 
arms decreasing faster than those with a smaller number. He used the original 
disk diameters for the determination of the specific rates of regeneration. If the 
final disk diameters are taken the specific rate of regeneration of each arm on the 
whole increases with increase in number of removed arms. The question as to the 
use of the original or the final disk diameters depends upon the interpretation of 
’ Studies on Tissue Growth. II. Journal of Experimental Zodlogy, vol, vi, pp. 433-469. 
