SYSTEM AND SUPJIARBNAL DODIES IN THE SPARROW. 



755 



median ganglia, partly or completely fused (text-fig. 11). These 

 are joined to the secondary ganglia by connectives of nervous 

 fibres. AVe have also found these median ganglia in a much 

 more advanced embryo. The ganglia lie above the aorta imme- 

 diately ventral to the vertebral column, the centra of which are 

 in process of developinent. On either side of them there occur 

 mesodermal masses, such as give rise to muscle in the adult, in 



Text-fiarure 11. 



Transverse section tlirough Sparrow B at point marked a-a in fig. 9 G. Tlie secon- 

 dary sympathetic ganglion is shown at Si/m.C. (2) and is connected with the 

 median fused ganglia of the primary sympathetic (Si/in.C.) (1) chain. 

 Ao. Aorta. Cj). Capillaries associated with primary sympathetic. 



(Sp. B 9, 4, 7 and 8.) 



this case probably to muscles attached to the vertebrre. Tlie 

 coi\nectives between the ganglia are associated with a rich 

 fcapillary plexus dorsal to the aorta. . 



Posterior to these ganglia the primary sympathetic cords 

 diminish in size, until in the abdominal region it is no longer 

 possible to trace them. 



Transvei'se sections throw light on the processes of develop- 

 ment above described; Text-figs. 10 a & 10 6 show transverse 



