EXPERIMENTS ON THE FORE LIMB OF AMBLYSTOMA 451 
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healthy. Transplanted limb has two well-marked digits and begin- 
ning of third. Limb not so long or so far advanced as the normal 
one. Good circulation. 
May 25. The specimen was preserved on account of the deformity 
of its back, which rendered its existence precarious (fig. 38). 
Transpanted limb is a left, having preserved its original laterality. 
It has a distinct third digit and the beginning of fourth, and on the 
radial side there is a reduplication of digits. The whole hand is, there- 
fore, nearly symmetrical. Transverse sections show a small coracoid 
and a very shallow glenoid fossa, but the scapular portion of the girdle 
is not developed. Differentiated muscle fibers are present in the limb, 
but no nerves have been found. 
Experiment Tr. Mes. 4. May 11, 1912. Right limb mesoderm to 
right side. 
May 15. Grafted tissue not very prominent. 
May 21. Limb bud ‘points’ anteriorly. 
May 27. Digitations beginning; dorso-ventral doubling. 
June 7. Specimen preserved. 
The arm as a whole is a left, i.e., its laterality has been reversed 
(figs. 39 and 40). The radial digit is reduplicated on the radial border. 
There is another reduplication consisting of a long digit and a nodule, 
mirrored from an ulno-palmar plane. 
In the normal limb on this side the first two digits are syndactylous, 
the first being short. 
Experiment Tr. Mes. 5. May 11, 1912. Mesoderm from right 
limb bud implanted on right flank. 
May 12. Wound still slightly open; transplanted tissue a good 
hump. 
May 21. Transplanted tissue has grown and points more distinctly 
anteriorly. 
May 27. Good circulation; two digits show; limb looks to be of 
normal form. 
June 7. Specimen preserved. 
Three well-marked digits are present with trace of fourth. The 
first two digits are webbed; otherwise the limb is normal (fig. 41). It 
is clearly a left, its original laterality having been reversed. There 
was no evidence of motility of the implanted limb before killing. 
The preserved specimen was cut into frontal sections, examination 
of which shows that the shoulder-girdle cartilage is fairly well formed; 
the ventral (coracoid) portion is more extensive than the scapula, which 
is only slightly developed. Pronephric tubules, seen near the base 
of the limb, indicate that part of the pronephros was transplanted with 
the limb cells. Muscle tissue is well developed in the limb, though no 
nerve fibers seem to be present. 
Experiment Tr. Mes. 16. May 13, 1914. Left limb mesoderm 
transplanted to right side. 
May 14. Perfectly healed; small nodule caused by transplanted 
tissue. 
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