SYSTEM AND SUPRARENAL BODIES IN THE SPAnilOW. 



765 



1810 by Tiedemann, but the occurrence of a, primary chain in a 

 position an.aUigous to that of the definitive sympathetic in othei* 

 vertebrates was not discovered till many years later by His. 

 Subsequent writers have all supported his findings, but hitherto 

 a,ll have failed to discover any genetic continuity between the 

 two formations. Ganfini (5), in his paper on the sympathetic in 

 birds, seems to have observed the relations more successfully 

 than his predecessors, but he failed to discover the origin of the 

 secondary ganglia from the dorso-lateral processes of the primary 

 ganglia. He follows his predecessors in deriving them imme- 

 diately from the dorsal root ganglia, for he writes : " Alia forma- 

 zione del cordone sinipatico primario segue la formazione di un 



Text-fiffure 20. 



D.R.G. 





. //^,- --.-0 



Transverse section of Sparrow G9 (= 8-(Iay chick), showing the diflTerentiation of 

 colls of the dorsal root ganglion (D.E.G.) and of the secondary sympathetic 

 ganglion (S^.G.). Sp.N. Spinal nerve. 



cordone simpatico secondario. Questo e formato da una serie di 

 gangli situati ognuno a livello della parte del tutto prossimale 

 del nervo spinale ed originati da neurociti derivanti esclusiva- 

 mente dai gangli spinali. ... Da ogni ganglio simpatico 

 secondario . si diparte un ramo che dirigendosi ventralmente e 

 medialmente connette il cordone simpatico secondario col pri- 

 mario." From the last statement he appears to have observed 

 connections proceeding froin the secondary to the primary 

 ganglia, while our graphic reconstructions show exactly the 

 opposite. 



The nearest approach to correct observation seems to have 

 been made by Miss Williamina Abel (1), though curiously enough 

 she attached little importance to it. In her paper we read : 



