TRANSPLANTATION OF LIMBS IN AMBLYSTOMA 149 
By comparing series HS4 with series HS5 (table 1b), it is 
noticed that limbs of the latter series exhibited no better function 
than did those of the former series. The superior function of 
the limbs in the series HS3 to that in the aforementioned series 
is explicable on the grounds of the close proximity of the trans- 
planted Lmb with the normal limb, which resulted in the ad- 
ditional limb’s receiving some nerve supply from the normal 
plexus. 
No cases of the series HS4 were sectioned. However, those 
of series HS5 which were sectioned showed that the main nerve 
supply came from segments corresponding to the position occu- 
pied by the transplanted limb; e.g., in case HS5» (fig. 22), which 
centered ventral to the eighth and ninth segments, the inner- 
- vation was derived from these same segments of the cord. This 
observation is in accord with those made by Braus (’04, ’05) 
and Harrison (’07) on anuran embryos, viz., that when the 
normal limbs are left intact the transplanted limb becomes 
innervated from that region of the cord corresponding to the 
position of the implanted limb rudiment. 
No experiments were made to test the function of additional 
dimbs transplanted the distance of six segments posterior to the 
normal intact limb. From the results obtained in the series 
HS4 and HS5 it appeared improbable that they should function 
to as great an extent as did those of the series above mentioned. 
Viewing these experiments as a whole, therefore, we see that the 
limbs functioned much more imperfectly than did the autoplastic 
limbs transplanted to the same relative positions, and also that 
their innervation was derived from segments of the cord corre- 
sponding to the position of the implanted limb rudiment rather 
than from segments situated anterior to the position occupied 
by the limb. The significance of these points will be considered 
more fully in the discussion. 
Regeneration 
Although the position and extent of the limb mesoderm can 
be quite accurately located by means of certain landmarks, it 
