92 EEPORT OF COMMISSIONERS OF INLAND FISHERIES. 



Other Parts of the Organism.— The beak will be renewed when broken 

 off. Regeneration was observed in various segments of the telson. 

 That the carapace possesses some power of regeneration seems to be 

 indicated by the fact that around holes made in the dorsal region of 

 the thorax the exoskeleton was partially restored after a moult. 

 Some of the gills were removed from several lobsters, but no regener- 

 ation was noted during the period of observation. 



It is thus seen that the ability to regenerate lost parts is remark- 

 ably extensive throughout the external structure and appendages. 

 No definite observations have yet been made on the power of regener- 

 ation in the internal organs. Future experiments in this direction 

 may furnish interesting data, especially in the case of internal or- 

 gans not exposed to injury. 



II. The Relative Power of Regeneration at Different 

 Levels in Thoracic Appendages. 



As has just been stated, the walking legs are always thrown off 

 by autotomy at the breaking plane between the second and third 

 segments. Now when it is considered that the regeneration of the 

 leg usually occurs at this joint the question is immediately suggested, 

 will the thoracic appendages regenerate at other levels either distal or 

 proximal to the breaking plane? 



For the purpose of answering this question the legs were cut at 

 the various levels indicated in Figs. Ill, V, Plate XXII. As shown 

 in Fig. V, the segment or basiopodite just below or proximal to the 

 breaking plane was cut at three different levels: pa indicates a 

 cut at the joint between the basiopodite and coxopodite; pb, a plane 

 through the middle of the basiopodite; and pc, a level just below 

 the surface of the breaking plane. Fifteen mutilations were made 

 below the breaking plane of the chelipeds and walking legs; seven 

 limbs were cut at pa, five at pb, and three at pc. Out of the fifteen 

 mutilations only three showed any regeneration, and those were at the 

 level p]:> or from the middle of the basal segment. 



Thirty-nine mutilations were also made at regions distal to the 



