NO: 2-4] LIMB-MUSCLES [N AMPHIBIA. Oy 
Kaestner ! has failed to show that the myotomes take any part 
directly in the formation of the limbs in the Anura. Neverthe- 
less, if I have understood him rightly, he still believes that the 
limb-muscles are derived directly from the myotomes, although 
he has not seen the process, owing, as he believes, to the very 
early period at which it takes place. 
Still more recently, H. H. Field? described myotome-proc- 
esses taking part in the formation of the muscles of the anterior 
limbs in the Urodela (Amblystoma, Triton). He has also 
extended his observations to several of the Anura (Rana, 
Bufo) with similar results. It is unnecessary to discuss in 
detail the origin of limb-muscles in the higher groups of verte- 
brates, as this has been very fully treated elsewhere in the 
literature on the subject. It is sufficient to say that, with a 
single exception, in all the higher vertebrates in which true 
muscle-buds have not been found masses of proliferated cells, 
which are regarded as homologous to muscle-buds, have been 
described. It was with the hope of definitely determining, if 
possible, the source of the muscles in the limbs of some of the 
Amphibia that the present investigation was undertaken, at 
the suggestion of Dr. R. G. Harrison. 
I gladly take this opportunity of acknowledging my many 
obligations to Dr. Harrison for the friendly interest with which 
he has followed my work, and for having placed at my disposal 
much of his own prepared material. I also take pleasure in 
thanking Prof. T. H. Morgan, in whose laboratory most of the 
work was done, for his kind criticism. My thanks are also 
due to Prof. C. O. Whitman, of the Marine Biological Labo- 
ratory at Wood’s Holl, Mass., where the work was completed. 
Material. 
The material used in the present investigation consisted of 
Urodela, Amblystoma punctatum, and several species of Triton, 
and of Anura, Rana sylvatica, Rana palustris, and Bufo ame- 
vicanus, collected in the vicinity of Bryn Mawr, Penn. 
1 Archiv f. Anat. u. Phys. (Anat. Abth.), Hefte 5 und 6, 1893. 
2 Anat. Anz., Bd. 9, 23, 1894. 
