No. 2.] LIMB-MUSCLES IN AMPHIBIA. i gf 
worden sind. Wir sahen bei Froschlarven aus der undifferen- 
zirten Extremitatenanlage sowohl Knorpel als auch Musculatur 
hervorgehen, scheinbar ohne Betheiligung der Myotome. Aber 
dies auch nur scheinbar, denn vorausgesetzt, dass die Myotome 
der Froschlarven ebenso wie die der iibrigen Wirbelthier Klas- 
sen die Grundlage der Extremitatenmusculatur abgeben, so 
muss bei den friihesten Stadien von Froschlarven, die ich bisher 
beschrieben . . . jener Vorgang langst abgeschlossen sein.”’ 
My own odservations agree with Kaestner’s, but his assumption 
that the limb-muscles must be derived from the myotomes is, 
I think, not supported by the facts of development as shown 
by experimental study. 
From the study of normal amphibian embryos, urodeles, and 
anurans, I was led to conclude that the limbs are wholly 
somatopleuric in origin, that the myotome-processes take no 
part in the formation of the limbs, but give rise exclusively to 
the musculature of the body-wall, and that there is no special- 
ized proliferation of cells from the myotomes in the limb-region. 
I determined to further test the somatopleuric origin of the 
limb-muscles by experiment. The experiments were made in 
the spring of 1895, on young tadpoles (Rana sylvatica), and on 
young Amblystomas (Amblystoma punctatumy). 
III. ExpeERIMENTS ON AMBLYSTOMA AND RANA. 
The method of experiment was as follows: Very young 
embryos in which neither the myotome-processes nor the limb- 
rudiments had begun to develop, were cut from their capsules 
and placed in a watch crystal on filter paper moistened with 
water. Then with a hot needle the ventral halves of the myo- 
tomes of the posterior limb-region on the right side of the body 
were destroyed. A few similar experiments were made with 
cold needles. These, however, gave no definite results, owing 
to complete regeneration, and the use of cold needles was aban- 
doned. All the operations were performed under a dissecting 
microscope. Since in Amblystoma the posterior limbs arise in 
the twentieth segment, the attempt was made to destroy the 
ventral edges of the myotomes from the sixteenth to the 
