A STUDY OF THE RATE OF REGENERATION OF 



THE ARMS IN THE BRITTLE-STAR, OPHIO- 



GLYPHA LACERTOSA. 



CHARLES ZELENY. 



Two interesting internal factors regulating the rate of regenera- 

 tion of the arms in the brittle-star, Ophioglypha lacertosa, were 

 discovered in the course of a study of the problem at the Naples 

 Zoological Station during the past winter (190203). As some 

 months must elapse before a full discussion of the results can be 

 published it has been thought advisable to give the general data 

 in a preliminary paper. This seems especially desirable at the 

 present time because of the high interest taken in the experi- 

 mental evidences of a far-reaching correlation between the parts 

 of the individual in both animals and plants. 



The experiments to be described give data which shoiv that tJic 

 rate of regeneration of the an/is varies on the one handivith the 

 size of the animal and on the other with the number of removed 

 arms. The first-mentioned correlation gives a maximum rate of 

 regeneration for the medium sized individuals with a pronounced 

 decrease for the smaller as well as for the larger ones. The second 

 correlation, with one exception to be mentioned, gives us an increase 

 in the rate of regeneration of an arm as we pass from the cases 

 with a smaller to those with a greater number of removed arms. 

 The series with all five arms missing is excepted in the statement 

 because the animals in this lot in every instance died or showed 

 evidences of decay before the completion of the experiment. 



Method. Forty-five perfect specimens were divided into five 

 equal groups of nine each, care being taken to distribute them in 

 such a way as to make the sets approximately equivalent as re- 

 gards size of individuals. The operation consisted in the removal 

 of one or more arms by a transverse cut at the disk level. In 

 the first series one arm was removed, in the second two contiguous 

 arms, in the third three contiguous arms, in the fourth four, and 

 in the fifth five arms. The animals were kept in ten " battery " 

 jars, two for each series, and were not fed during the whole period 



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