SYMPATHETIC GANGLIA 247 



no obvious relationship to the spinal nerves may be frequently- 

 observed in proximity with the aorta where the sympathetic trunk 

 arises. It is not incredible, therefore, that a student of Goette 

 should have concluded that these cells are differentiated in situ 

 from the mesoderm. However, the fact that sections of early 

 larvae may not show a direct relationship of the cells constitu- 

 ting the anlage of the sympathetic trunk to the spinal nerves does 

 not afford conclusive evidence that no such relationship exists. 

 The earliest fibers of the communicating rami are exceedingly 

 delicate and might readily escape notice except in the most suc- 

 cessful preparations. Furthermore, it is not impossible that 

 cells might deviate from the course of the spinal nerves and wander 

 toward the aorta in advance of the growing fibers of the communi- 

 cating rami. 



By careful study of good preparations, as the writer has shown 

 in a series of earlier papers, cells may unmistakably be traced 

 peripherally along the spinal nerves and into the primordia of 

 the ganglia of the sympathetic trunks. Some of these cells re- 

 tain their capacity for cell division after they have become sepa- 

 rated from the cerebro-spinal nervous system and undergo mitosis 

 along the path of migration or in the primordia of the sympathetic 

 ganglia. These phenomena, it should be stated, may be more 

 readily demonstrated in embryos of vertebrates of other classes 

 than in larvae of the Amphibia. 



The genetic relationship of the ganglia of the sympathetic trunks 

 to the cerebro-spinal nervous system will not be further considered 

 at this time. The cumulative evidence in favor of this view af- 

 forded by the work of not a few investigators seems to the writer 

 conclusive. 



THE TURTLE 



Ciliary ganglion 



The most complete observations on the development of the 

 ciliary ganglion in a reptilian type which have been recorded are 

 those of Beraneck and Hoffmann. Both these investigators 

 studied the development of this ganglion in embryos of Lacerta 

 agilis. 



