122 Cc. V. MORRILL 
that a certain amount of activity in the limb is necessary to 
start the regenerative process. Wendelstadt also tried the 
effect of leaving a small piece of one of the bones (ulna) in situ. 
For this operation he used one Axolotl and one Triton. In the 
latter the humerus was also wounded. The axolotl regenerated 
a new ulna which was shorter than normal while in the Triton 
a whole new forearm and a second hand were formed. This 
peculiar malformation in the Triton was never duplicated in 
any of the writer’s experiments on Diemyctylus, although in 
some cases the femur was purposely wounded. It is improbable 
that there is any difference in the power of regeneration of fore 
and hind-limbs in these animals. 
Experiment 5. Extirpation of the fibula and removal of the 
foot entire without injury to the femoral epiphysis or tibia. Num- 
ber of animals, five:—In this lot two were killed at sixty-six 
and ninety-five days respectively and the remainder at the end 
of a year. The first of these had regenerated a well-marked foot 
when killed and a new fibula. The latter consisted of a solid bar 
of cartilage with a layer of subperiosteal bone surrounding its 
proximal two-thirds. It was attached to the femoral epiphysis 
by a capsule, common to it and the tibia. Distally it was 
connected with the new tarsalia by ligaments, in places showing 
the beginning of a joint cavity. In the specimen killed at 
ninety-five days, the foot had regenerated but there was scarcely 
any indication of a new fibula. The remaining three specimens 
killed after one year regenerated a new complete foot including 
tarsalia and a new but incomplete fibula. A section through one 
of these is shown in figure 8. The old tibia (7%b.) articulates 
with the femoral epiphysis (/p.f.) while the new fibula (F7b.n.) 
falls short proximally. Peripheral ossification has started in 
the new element but there is no marrow cavity as yet. The new 
tarsalia are seen at 7.c.n. The distal epiphysis of the tibia 
seems to be composed of new cartilage like that of the tarsals 
and fibula. This is to be expected since it was shown that the 
old epiphysis in a stump is always replaced by new cartilage 
(vid. Part I). In the present experiment one would expect 
first a new formation of cartilage from which a new tibial epi- 
