THE SOMITES OF THE CHICK 61 



the CutislameUe (dermatome) is converted into the connective 

 tissue of the dermis. At the same time Hatschek proposed to call 

 Remak's Wirbelkernmasse the sclerotome. 



In the same year Paterson ('88) discovered that the ventral 

 edges of the dermomyotomes of the trunk of the chick grow down- 

 ward into the memhrana re^iidens inferior and so supply the muscu- 

 lature of the abdominal and thoracic walls, but that the muscula- 

 ture of the limbs does not arise directly from the dermomyotomes. 

 Paterson saw that the dermomyotome is composed of two lam- 

 ellae but did not discover that the outer lamella contributes to the 

 dermis. 



Kaestner ('90) upon insufficient grounds attacked the work of 

 Rabl and Paterson. He believed that some of the cells of the cutis 

 plate become myoblasts and that the remainder form an epithe- 

 lium which is destroyed during the third day by parablastic 

 tissue. He further maintained that the Muskelknospen, or grow- 

 ing ventral edges of the dermomyotomes, described first by 

 Paterson, contribute directly to the musculature of the limbs. 



Kollmann ('91) describing the somites of human embryos, 

 asserted that whereas the muscle plate, or inner layer of the 

 dermomyotome, supplies the dorsal musculature of the trunk, 

 the cutis plate gives rise to the ventral body musculature and to 

 that of the limbs. He admitted, however, that dermal connec- 

 tive tissue arises from the myotomes (dermomyotomes?) of the 

 trunk. 



Fischel ('95) took a somewhat intermediate position between 

 Rabl and Paterson on the one hand and Kaestner and Kollmann 

 on the other. He pictured the growing dorsal and ventral edges 

 of the dermomyotome in the chick and showed that the prebra- 

 chial dermomyotomes do not have ventral growing edges. The 

 ventral buds or growing edges of the dermomyotomes of the 

 trunk, he thought, break up into loose tissue which mingles with 

 the mesenchyma of the nephrotome and lateral plate. The 

 muscles of the limbs and of the ventral part of the body wall arise 

 in the mass of tissue formed in this way, and Fischel judges from 

 analogy that these muscle masses probably arise from the 

 dermomyotome. 



