124 BYRNES. [VoL. XIV. 
muscle has regenerated so as to occupy an almost normal 
position at the anterior limit of the limb; it does not, however, 
extend throughout the entire limb-region, as is the case in 
normal embryos. The limb-rudiments are well developed and 
normal. In another embryo killed eleven days after injury the 
myotomes have been reduced to almost one-half their original 
length. The abdominal muscle-rudiment has regenerated, but 
is present in the limb-region only at the extreme anterior limit 
of the right limb. Both limb-rudiments are normal. 
An embryo killed thirteen days after injury shows that the 
myotomes of the posterior limb-region on the right side of 
the body have been reduced to one-third their original length. 
The right abdominal muscle, though present, is reduced in 
size and shortened. Notwithstanding the abnormal conditions 
in the myotomes and the abdominal muscles, the limbs are 
well developed and normal. 
Figs. 21-25 represent sections through an embryo killed 
twenty-six days after injury. Owing to the distortion that 
has resulted from the mutilation, the sections do not show cor- 
responding regions of the right and left limbs. The limbs 
extend, however, over an equal number of cross-sections, and 
are apparently in every way similar. Fig. 21 is taken through 
the mid-region of the limb on the injured (right) side of the 
body. . The myotome is reduced and the abdominal muscle- 
rudiment is wanting. The limb is well developed and normal. 
Fig. 22 shows a more anterior section through the most anterior 
part of the right limb, which is represented, in this section, by 
only a few cells in the dorsal wall of the coelom. The myo- 
tome has begun to regenerate ventrally, but has not as yet 
reached the level of the limb. 
Fig. 23 is taken directly in front of the limb-region. It 
shows the ventral growth of the myotome from which the 
abdominal muscle is to be, at least in part, regenerated. The 
relations of the abdominal muscle in still more anterior sections 
are represented in Figs. 24 and 25. These sections plainly 
show that the myotomes are still greatly reduced and that their 
ventral regions of proliferation must have been completely 
destroyed when the injury was first made. The limbs are, 
