OCR Text |
Show 1897.] OE THE LEGS IN THE BLATT1D.E. 909 cases were the reproduced parts at all malformed. These will be dealt with later on. The balance of 848 cases in which reproduction was not observed is accounted for by no reproduction occurring at ecdysis or by death before ecdysis. The recent observation by Bordage1 that the reproduced tarsus of certain Bhasmids is invariably four-jointed is of much interest in connection with the above results. (d) Llubllitg to accidental injury In immature individuals. The evidence already obtained that the occurrence of the four-jointed tarsus in a captured Cockroach indicates accidental injury in the part, was confirmed indirectly by the examination of 1106 young of S. orientalis, when first caught, with the result that *8°/0 were found to be imperfect as regards either the whole or portions of one or more legs. This is a considerably lower percentage than that for the occurrence of four-jointed tarsi recorded in Table B, but the importance of the frequent occurrence of imperfect individuals is increased by bearing in mind that reproduction of lost parts may take place at any of the several ecdyses and that, as has been ascertained by observation, when once a four-jointed tarsus has appeared it is perpetuated through the succeeding ecdysis and almost certainly though all subsequent ones up to their cessation on maturity being attained, which accounts for the higher percentage of such tarsi found in adult individuals. From another point of view the relation of abnormal tarsi to accidental injury in captured individuals is emphasized by comparing Table I) with the following results of examining newly captured S. orientalis for the distribution of imperfect legs : - Pair. I II Ill The long third pair of legs seems to suffer more from their exposed condition as compared with the less extended anterior pairs, and this was observed to be the case with individuals kept in confinement. The tarsi of these, if subsequently reproduced, were invariably four-jointed. Newport2 has noticed a similar special liability to injury in the long posterior legs of Scolopendra. It is of course possible that tbe four-jointed form of tarsus may be occasionally of congenital origin, but the balance of evidence indicates clearly that in S. orientalis, at all events, it is a result of the loss of the normal tarsus. 1 " Sur la regeneration tetramerique du tarse des Phasmides," Compt. Rend. Acad. Sci. seance de 28 Juin, 1897. 2 "On the Reproduction of Lost Parts in Mynapoda and Insecta, Phil. Trans. 1844. )2 young. 25% 32*6 % 42*4% 131 adults. 20*6% 19*1 % 60*3 % |