910 ME. H. H. BRITTDIiET ON THE REGEXERATIOX [NoV. 30, 



Numerical variations in the joints of reproduced appendages 

 have been described by several oljservers in other Orthoptera than 

 the Blattidae and in certain other groups ol the tracheate Arthro- 

 poda. As has been pointed out, the phenomena o£ reproduction 

 of the legs and the special features of the peculiar form of tarsus 

 associated therewith in the Cockroach must be considered with 

 some reference to what is known of the reproduction of lost parts 

 in the Arthropoda generally. The close connection between the 

 phenomena of reproduction of appendages and ecdysis permits the 

 insertion at this place of certain facts noticed during the mutilation 

 experiments already briefly described. 



Immediate effects of mutilation. — A drop of blood appenred on 

 the cut or ruptured surface of the leg, but clotted in a minute or 

 two, thus preventing further hajmorrhnge. The loss of part or 

 the whole of the leg seemed to inflict mechanical inconvenience 

 only, and an individual which had lost portions of three legs moved 

 about on recovery from anaesthesia with fair activity and resumed 

 its normal habits at once. It was noticed that in nearly all cases 

 the remaining portions of a partially removed tarsus were very 

 soon dropped off, the tibia then terminating the limb. The 

 remaining half of a divided tibia was sometimes dropped and 

 sometimes retained. These losses of parts proximal to the 

 artificially injured region never occurred simultaneously with the 

 inflicted injury. In considering this matter it is necessary to bear 

 in mind the fact that Arthropods of several groups have the power 

 of throwing off their appendages in response to stimuli of various 

 kinds, a phenomenon to which the name autotomy has been given. 

 In Cockroaches there seemsto exist a very slight degree of autotomy. 

 If thrown into boiling water they do not snap off their legs as is 

 the case, for instance, with many Spiders. On the other hand, a 

 Cockroach held by a leg not infrequently escapes by its separation 

 from the body when no particularly strong pull is made by the 

 forceps holding the limb, and with a suddenness suggestive of 

 autotomy. Moreover, it was noticed that the break occurs, 

 invariably, either at the tarso-tibial articulation or (and much 

 more frequently) at the suture where femur and trochanter are 

 fused. But if a certain degree of autotomy be admitted, it must 

 be remembered that, in a Cockroach preserved in spirit, a break 

 is effected easily at either of the above-mentioned places, while a 

 strong pull with the forceps is necessary to separate femur and 

 tibia. If the body be held and the tarsus palled, the break occurs 

 at the femoro-trochanferic suture, while if the femur be held 

 instead, a pull on the tarsus is followed by its separation from the 

 tibia. 



I cannot find any record of observation on this point in the 

 Blattidae, but in the case of the Phasmidse, 8cudder ' observed that 

 in Diapluromera amputation of any portion of a leg distal to the 

 femoro-trochanteric suture was followed by loss before the next 



' Proc. Boston Nat. Hist. Soc. 18(59, xii. p. 99. 



