SYSTEM AND SUrilAllENAL BODIES IN THE SPARROW. 



747 



In collaboration with 0. V. Batson lie experimented on chick 

 embryos. By electrolysis they destroyed the dorsal part of the 

 neural tube of the embryos, and in four successful cases found 

 that the sympathetic primordia were formed to a greater or less 

 extent. Kuntz later carried out further work on the same lines 

 and arrived at similar results. Of similar experiments carried 

 out on tadpoles, by actual dissection, he writes : " As far as the 

 study of the development of the sympathetic trunks was pursued 

 in these embiyos the findings corroborated those in the operated 

 embryos of the chick." 



The experimental investigations of E. Miiller and Sven Ingvar 

 (13), on the other hand, support the conclusions of His and Held. 



Text-figure 5. 



o.R. G. 



mm 



M.c: 



Transverse section of Sparrow embryo 11 (= chick about 78 hrs.), showing cells 

 leaving tlio spinal cord by the ventral nerve root. 



JJ.E.G. Dorsal root ganglion. M.C. Migrating cells. S.C. Spinal cord. 

 V.E. Ventral root. ' (Sp. 11, 4, 2, 17.) 



They carried out their experiments on Amphibian material. By 

 destroying the ventral part of the neural tube they found that 

 the sympathetic was still formed, while the removal of the dorsal 

 portion resulted in its failure to develop. They thence conclude 

 that the primordia of the sympathetic nervous system arise from 

 the spinal ganglia. 



The conflicting results obtained by these workers illustrate the 

 pitfalls inherent in the experimental method as applied to this 

 particular problem. 



Our observations certainly do not support Held's view as to 

 the exclusive origin of the sympathetic system from the dorsal 



