240 ALBEKT KUNTZ 



Fibrous connections have become established with the sympa- 

 thetic trunks as well as with the cceliac and the hypogastric 

 plexuses. It is interesting to note that all these sympathetic 

 nerves still contain numerous "accompanying" cells which are 

 apparently migrating peripherally along their fibers. It is prob- 

 able, therefore, that cells wander down from the sympathetic 

 trunks into the myenteric and the submucous plexuses after these 

 fibrous connections are established. 



(c) Pulmonary plexuses. — In transverse sections of embryos 

 6 or 7 mm. in length, some of the cells which wander from the 

 vagus trunks toward the oesophagus, in the region of the bifurca- 

 tion of the trachea, are carried out along the anterior and the dor- 

 sal surfaces of the bronchi. These cells obviously give rise to the 

 anlagen of the pulmonary plexuses. 



(d) Cardiac plexus. — The first unmistakable evidence of gan- 

 glia pertaining to the cardiac plexus is found in embryos about 12 

 mm. in length. In transverse sections through the anterior 

 region of the heart, small groups of nervous elements are observed 

 ventral to the trachea (fig. 14, car.p.), a few of which have pene- 

 trated deep into the angle between the aorta and the pulmonary 

 artery. These cell-aggregates constitute the anlagen of the earli- 

 est ganglia of the cardiac plexus. They are without fibrous con- 

 nections as yet, but a few short fibrous branches are seen to arise 

 from the vagus trunks and the left recurrent nerve, which extend 

 toward the heart (fig. 14, earn). These are obviously the earliest 

 cardiac nerves. Their fibers are still loosely aggregated and are 

 accompanied by numerous cells, some of which appear to escape 

 at the tips of the nerves and to migrate toward the cardiac gan- 

 glia in advance of the growing fibers. Nerves cannot be traced 

 as yet from the sympathetic trunks toward the heart, and there 

 is no evidence of the migration of cells from the sympathetic 

 trunks into the anlagen of the cardiac plexus. 



In embryos 16 mm. in length, branches of the vagi as well as 

 cardiac nerves having their origin in the sympathetic trunks may 

 be traced into the ganglia of the cardiac plexus. Here again it is 

 interesting to note that while the branches of the vagi are appar- 

 ently free from migrating cells, the cardiac nerves having their 



