56 H. V. NEAL 



cells to be derived from the dorsal ganglia and the ventral nerve 

 roots. In sections of later stages (15 mm. embryos) the anlagen 

 of the sympathetic ganglia may be seen as clusters of similar 

 cells attached to the nerves at the level of the aorta. The deeply 

 staining cells of the mesenchyma are now less numerous. He 

 therefore infers that they have entered into the formation of 

 the ganglia. Proof that the sympathetic anlagen are not the 

 product of the continued migration of cells from the dorsal and 

 ventral roots is not presented. As to the evidence of migra- 

 tion, Kuntz is able to obtain such kinetoscope effects as the 

 following: '^ numerous cells (in a 10 mm. embryo) push out from 

 the ventro-lateral angles of the neural tube and migrate periph- 

 erally along the paths of the motor nerve-roots." That such 

 cells enter into the formation of the sympathetic ganglia he thinks 

 is proved by the following considerations (p. 206) : 



As my observations on the early stages of embryos of Acanthias 

 have shown, numerous cells migrate peripherally both from the neural 

 crest and from the ventral part of the neural tube before the fibers 

 of the ventral nerve-roots can be traced peripherally to the level at 

 which the sympathetic trunks arise. These cells later become ag- 

 gregated to form the anlagen of the sympathetic trunks. In view 

 of these facts it can not be doubted that in embryos of Acanthias many 

 cells which have their origin in the ventral part of the neural tube 

 enter the anlagen of the sympathetic trunks. 



While there seems little reason to doubt that cells of somatic 

 motor nerve anlagen in Squalus participate in the formation of 

 the neurilemma, convincing evidence that they migrate into the 

 anlagen of the sympathetic is wanting. The assertions of Kuntz 

 in this connection appear quite unconvincing. In the numerous 

 papers by this investigator which have appeared in rapid suc- 

 cession in recent years, covering the development of the sympa- 

 thetic in all classes of vertebrates except amphibia, observations 

 and conclusions, sense impressions and inferences are indiscrimi- 

 nately advanced as 'observations.' Kuntz, for example, does 

 not bring forward the slightest evidence to prove the assertion 

 ('11, p. 183) that ''the cells which migrate peripherally from the 

 neural crest and the neural tube .... become scattered 

 in the mesenchyma of the region lying between the lateral mus- 



