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Show 910 MR. H. H. BRINDLEY ON THE REGENERATION [Nov. 30, Numerical variations in the joints of reproduced appendages have been described by several observers in other Orthoptera than the Blattidae and in certain other groups of the tracheate Arthro-poda. As has been pointed out, the phenomena of 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 appeared on the cut or ruptured surface of the leg, but clotted in a minute or two, thus preventing further haemorrhage. 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 wdth 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 seems to 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 aud the tarsus pulled, the break occurs at the femoro-trochanteric 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 Bbasmidae, Scudder1 observed that in Diupheromeru amputation of any portion of a leg distal to the femoro-trochanteric suture was followed by loss before the next 1 Proc. Boston Nat. Hist. Soc. 1869, xii. p. 99. |