[Regeneration of X-irradiated limbs ofPleurodeles waltlii Michah. (Urodele). The influence of quality and orientation of non irradiated grafts].

X-irradiation suppresses the morphogenetic power of limb tissues. Transplantation of non-irradiated tissues onto an irradiated limb allows, one to study the influence of the grafts qualities (viz. dorsal, ventral, anterior and posterior qualities) and the influence of the orientation of these grafts both on the degree of development and on the orientation of the regenerates. Either limb tissues or flank tissues were grafted. Either four or two or one quality were represented in the limb tissue grafts, while various orientations and locations were imposed upon them. 1. When four qualities (dorsal, ventral, anterior and posterior) were present in the grafts, regeneration was generally normal and complete. When two qualities (dorsal and ventral) were present the rate of normal or subnormal regeneration was 66%, with differentiation of all skeletal parts of the regnerarates. When only one quality (dorsal or ventral) was present regenerates were deficient or absent, and differentiation of carpus and zeugopod bones was never observed. At least two opposite qualities are necessary to allow regenerates to develop. 2. When we graft skin cuffs on irradiated limbs, the proximo-distal development of the regenerates depends only upon the proximo-distal level of the non-irradiated limb from which the graft was taken. 3. The orientation of regenerates is like that of the grafts. 4. 90‡ rotation of the skin has no influence on regeneration.