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THE AMERICAN NATURALIST [Vol. XLII 



between the distal end of the leg-hone and the proximal 

 (now inverted) end of the graft it was possible to detect 

 with greater precision the source of the material for the 

 new bones. The presence of a single bone instead of two 

 as in the former case also simplified the conditions. 

 Despite these advantages, only a few cases were obtained 

 in which the results seemed to show with great proba- 

 bility that all of the material for the new skeletal parts 

 was derived from the exposed proximal end of the 

 grafted piece. In such cases there was always established 

 a cartilaginous connection between the cut distal end of 

 the femur of the stump and the cut distal end of the 

 grafted piece. The new limb is thus made up of a proxi- 

 mal piece of the femur, connecting cartilage, grafted 

 piece of reversed femur, new tibia, fibula, tarsalia and 

 phalanges from the proximal end of the grafted piece. 

 Evidences of absorption are generally seen in the grafted 

 piece. How far this might ultimately go was not de- 

 termined. 



Tail in Leg and Leg in Tail 

 By means of the skin-pocket-method it is easily pos- 

 sible to graft a short piece of the tail (without skin) 

 into a pocket of the leg, and vice versa, a piece of the leg 

 into a skin pocket at the cut end of the tail. I have made 

 a few such experiments with Spelerpes ruber not without 

 hopes that from the graft in the leg a tail might develop, 

 and a leg from the end of the tail. The results proved 

 otherwise, for, whenever regeneration occurred, the new 

 material for a new leg came from the cut end of the old 

 leg-bones the proliferating cells passing to one side of 

 the grafted piece and the latter becoming absorbed. 



A similar process occurred in the case of a leg grafted 

 in a tail; a new tail and not a leg regenerated. The 

 experiment shows that care must be exercised in inter- 

 preting the other cases where the same kind of organ 

 is grafted in a reversed position. 



