32o NOTES AND COMMENTS [November 



Regeneration in Orthoptera. 



Me. Edmund Bordage, of Reunion, although recently laid aside by 

 fever, continues to send home notes in regard to regeneration in Phas- 

 midae, Mantidae, Blattidae, and other Orthoptera. Their theoretical 

 interest is so great that we venture to refer at some length to two or 

 three recent papers by this observer. 



In twenty-five species of Orthoptera with five-jointed tarsus, re- 

 presenting twenty-one genera and three families, the regenerated tarsus 

 has only four joints. The number given in his published paper is 

 eighteen species, but a manuscript note on the copy sent us states it 

 at twenty-five. 



In Phylloptera laurifolia and Conoc&phalus differens (Locustidae), 

 Acridium rubellum (Acrididae), and Gryllus campestris (Gryllidae), 

 there is no trace of regenerative capacity in connection with the 

 posterior legs, which are used in jumping. This appears at first sight 

 an argument against the generality of Lessona's law, since these hind 

 legs are surely much exposed to the bites of enemies, besides being- 

 liable to injury in the moults. Bordage's answer is that the loss of 

 these limbs makes moulting extremely difficult, exposes the insects to 

 great danger at the hands of their enemies, prevents copulation, and 

 places the unfortunates at a great disadvantage in preferential mating. 

 He concludes that jumping Orthoptera which have lost their hindmost 

 legs are unable to propagate, and that this explains the absence of 

 regenerative capacity in this particular case. 



In another paper (Conqrtes Rendus Acad. Sci. Paris, cxxix. 1899, 

 pp. 169-171), Bordage points out that it is impossible to provoke 

 autotomy of the first two pairs of legs in saltatorial Orthoptera. By 

 main force a separation may be effected at the articulation of trochanter 

 and coxa, or rarely at the articulation of femur and trochanter. The 

 mutilation is often fatal, but if the insect survives and is still larval, 

 regeneration may be effected, perfectly if the separation was between 

 femur and trochanter, more or less rudimentarily if between trochanter 

 and coxa. 



This raises a double difficulty for those who uphold Lessona's law : 

 — (1) the regeneration seems to occur at points where mutilation 

 cannot be naturally effected ; and (2) the regeneration is most frequent 

 and most complete when the separation has been effected along the 

 line where rupture is rarest. 



Bordage gets over the difficulty by pointing out that in the 

 " exuvial autotomy," i.e. self-mutilation during a moult, the separation 

 is most frequent along the femur-trochanter articulation, and very rare 

 along the trochanter-coxa articulation. The bleeding is insignificant 

 in the first case, but it may be fatal in the second. Moreover, re- 

 generation in the first case is frequent, and, though slow, sometimes 



