No. 2.] LIMB-MUSCLES IN AMPHIBIA. 123 
An embryo killed eight days after injury shows the right 
myotomes reduced to one-half their original length. In the 
posterior part of the body, where the abdominal muscle and the 
myotomes remain permanently connected, the myotome has 
begun to regenerate dorso-ventrally. In front of this place 
of connection, however, the myotomes give little evidence of 
any dorso-ventral growth. The regenerating abdominal muscle 
has already developed well-marked muscle-fibrils, and both the 
limbs are normal. 
An embryo of an unknown species of frog killed nine days 
after injury shows a marked reduction in the size of the 
myotomes; it also shows a normal development of the limbs. 
Pl. XI, Fig. 41 a, shows a section through the posterior part 
of the posterior limb-rudiment of this embryo. On the normal 
(left) side of the body the abdominal muscle has not, as yet, 
been constricted from the myotome. The limb-rudiment is well 
developed. On the injured (right) side, the section shows the 
right myotome almost wholly destroyed, and with it also the 
abdominal muscle-rudiment. The injury has also involved 
the medullary tube, no trace of which remains in the limb- 
region. Notwithstanding the extent of the injuries, the right 
limb-rudiment is apparently normal. Fig. 41 6 represents a 
section through the anterior limit of the posterior limb of the 
same embryo. On the uninjured side of the body the abdomi- 
nal muscle-rudiment has not as yet come in contact with the 
limb. On the injured side the myotome is still greatly reduced, 
but shows a tendency to regenerate toward the limb-region. 
Although the myotome is not wholly destroyed on the right 
side of the embryo, it is so mutilated that it is scarcely con- 
ceivable that the few remaining muscle-cells could contribute 
cells to the limb, even if they did so normally. The limb- 
rudiments are, however, equally large on both sides of the body, 
as is shown in Fig. 44, which represents a camera drawing of 
the limb-region indicated in Fig. 41 a. 
Sections of an embryo killed eleven days after injury show 
that the outline of the body has not been distorted. The 
injured myotomes on the right side of the body extend ven- 
trally only to the level of the notochord. The abdominal 
