Regeneration and the moulting cycle in. Blattella germanica l. iii. Successive regeneration of both metathoracic legs

Abstract

At 29°C, 70 per cent. relative humidity, removal of the left and right metathoracic legs in succession, at intervals of 1, 2, or 3 days, in first instar Blattella germanica of known age∽, results in the appearance at the first moult of: (a) Two asymmetrical papillae, the timing of the moult being undisturbed; or (b) A regenerate on the left and a papilla on the right side, the time of moulting being determined by age at the first operation and independent of the second; or (c) Two asymmetrical regenerates, the time of moulting being then determined by age at the second operation and independent of the first. In (b) and (c) the rather constant size of regenerates from the first operation exceeds that of regenerates derived from either unilateral or simultaneous operations, while the smaller regenerates from the second operation in (c) show wide but erratic variation in size, not regularly related to the timing of the operations or the moult. In about 2 per cent. of the material, the second operation only gives rise to a structure intermediate between a papilla and a complete regenerate. Such rare exceptions to the "all or nothing" principle can appear only when ecdysis occurs during the exceedingly rapid process of differentiation of the blastema into a regenerated leg. This proceeds proximo distally in these individuals, in contrast to animals producing a regenerate and a papilla at their first moult, where the rapid differentiation of the blastema contained within the papilla and its coxa occurs, early in the second instar, in the opposite (i.e. distoproximal) direction. These results conform closely to predictions derived from the initial hypotheses put forward regarding the relationship between regeneration and the moulting cycle. New information on the regeneration process has also been obtained. © 1954 ASEG.