Experiments in Transplanting Lnnhs 249 



early stages of development in order that the nerve fibers may 

 afterward differentiate; then to explain the greater thickness of 

 the intrinsic nerves of the transplanted limb in comparison with 

 the connecting nerves within the body of the host, it is assumed 

 that nerve fibers may develop autochthonously within the limb 

 without having any connection with the nerve centers; finally to 

 account for the reduction of the number of fibers within the trans- 

 planted limbs after myelinization sets and the muscles become 

 functional, the connection with the center is again supposed to be 

 necessary. A change of this kind in the necessary conditions 

 governing the well-being of the nerve fiber is, on its face, extremely 

 improbable and any theory requiring such inconsistent assump- 

 tions for its support, as the Hensen theory seems to require in this 

 case, must be regarded as altogether unsatisfactory. 



We may now pass to the consideration of the work of Banchi, 

 who claims to have found within transplanted limbs nerves which 

 had no connection whatever with the nerves of the host. Ban- 

 chi's method of procedure is somewhat different from that of Braus, 

 one difference being that younger embryos were used for the 

 experiments. It is, however, an error to maintain that the pieces 

 transplanted contain no traces of vessels or nerves,-" for spinal 

 nerves reach at the stage in question the primary abdominal 

 muscle, which skirts the hind limb rudiment and which Banchi 

 shows in his figure. These nerves may be readily observed in 

 well stained sections, though it is necessary to use high powers of 

 magnification to bring them out clearly. They may also, be 

 readily demonstrated in preparations of the abdominal walls zn toto. 

 What Banchi has gained over Braus by operating on earlier stages 

 he has lost in using such extensive pieces. It is probable that the 

 pieces which the former transplants contain more nerve fibers and 

 Schwann cells than those of which Braus has made use of. When 

 we examine Banchi's experiments we find that out of twenty-nine 

 cases which are described there are only two in which the trans- 

 planted limbs contain nerves purporting to have no connection 



^This is maintained in one place though in the conclusion the statement is considerably modified. 

 Cf. Banchi '05, pp. 675 and 689. 



