118 S. R. DETWILER 
Apparently in all these cases the function of the limb was 
greatly restricted, and in no case cited was there any adaptive 
or codrdinated movements. Harrison (’07, p. 256), in describing 
his first experiment, says in regard to the function of an aneuro- 
genic limb, ‘‘No attempts were made to stimulate electrically, 
but spontaneous movements, though slight, were unmistakable.” 
Both Braus and Harrison observed that, regardless of the 
segmental nerve contribution, the architecture of the intrinsic 
nerve distribution is exactly the same as that in a normal limb. 
This is not an unusual phenomenon, for we know that in both 
normal and transplanted limbs, nerves reach the limb when it 
is still in the blastema stage. The union of the nerve with the 
differentiating limb system is made very early, so that in either 
case the final plan of nerve distribution is patterned according to 
skeletal-muscular differentiation and growth, probably in ac- 
cordance with Naussbaum’s law: that the course of the nerve 
within the muscle is an index of the direction in which the muscle 
has grown. 
The experiments to which reference has thus far been made 
were carried out on the anuran embryo, Bombinator being used 
by Braus, Bufo vulgaris by Banchi and Gemelli, and Rana 
sylvatica and Bufo lentiginosus by Harrison. In the majority 
of cases the limb buds were transplanted at a stage when the 
peripheral nerves were in part or completely developed. Ac- 
cordingly, when the wound in the host was made for the reception 
of the transplant, the terminal branches of the nerves of that 
region were severed and the implanted limb rudiment was placed 
in close apposition to the cut ends. Although these nerves so 
disturbed were originally intended to innervate other muscles, it 
was found that they would readily grow into the implanted 
embryonic rudiment and innervate the differentiating limb mus- 
cles as do the nerves in the normal situation. This fact would 
indicate that there is no specificity of a given motor neurone 
for any particular muscle fiber, so that the ultimate distribution 
and connection of the nerve fiber cannot be an intrinsic factor 
of the neurone. 
