REGENERATION 



177 



degree of determination in the regeneration buds. Young buds, 

 which have just become visible as half-spherical outgrowths 

 are resorbed if transplanted into the flank of another animal 

 of the same age. Older buds, on the other hand, go on devel- 

 oping, and produce approximately the same parts as they would 

 have formed if they had not been transplanted. A young re- 

 generation bud of a fore-limb, grafted onto the stump of an 

 amputated hind-limb, develops into a hind-limb regenerate 



Fig. 64. Transplantation of a regeneration bud. (a) amputation of 

 a fore-limb. If the regeneration bud alone is transplanted onto the 

 stump of an amputated hind-limb (d), it will form a hind-limb (e), 

 but if part of the original stump (hatched) is transplanted as well 

 (b), a fore-limb will be formed by the graft (c). After Przibram. 



(Milojevic, 1924), (Fig. 64, d-e). A young tail regeneration 

 bud produces a fore-limb if grafted into the neighbourhood 

 of a fore-limb, though an older tail regeneration bud develops 

 into a tail (Weiss, 1927). Conversely, a young limb regeneration 

 bud forms a tail if transplanted onto the base of a tail (Guyenot, 

 1927). These experiments show that young regeneration buds 

 are still more or less indifferent, and not yet determined for a 

 definite course of development. After transplantation, they 

 develop in agreement with their new environment, evidently 



Raven - Outline Physiology 



12 



