386 



This caused him to believe that the ganglia of the cardiac plexus are 

 composed exclusively of cells which have migrated thither from the 

 ganglia of the sympathetic trunks. 



The above observations prove conclusively that in the pig the 

 earliest anlagen of the cardiac plexus are composed of cells which 

 migrate thither from the vagus trunks. This is probably true of all 

 mammals. In the human embryo of His jr., referred to above, the 

 cardiac plexus was already connected with both the ganglia of the 

 sympathetic trunks and the vagus trunks by nerve-fibers. The an- 

 lagen of the cardiac ganglia would probably have been found con- 

 siderably earlier. 



My observations on the later development of the cardiac plexus 

 in the pig show no essential deviation from the description of His jr. ^) 

 for the human embryo, except that the earliest sympathetic nerves 

 are less intimately associated with the vagus nerves and enter the 

 cardiac plexus independently. His jr. has also found this to be the 

 case in the cat. 



nb. 





4. Vagus nerves. 

 The cells which constitute the anlagen of the myenteric and sub- 

 mucous plexuses, the pulmonary plexuses, and the cardiac plexus have 

 thus been traced to their origin in the vagus ganglia and the walls 

 of the hind-brain. Is this source sufficient to account for the multi- 

 tudes of nervous elements found 

 in these plexuses before such 

 elements can be supplied from 

 the ganglia of the sympathetic 

 trunks? 



In sections taken at right 

 gc- angles to the trunk in the head 

 region of embryos 10 mm in 

 length, medullary cells are ob- 

 served migrating from the walls 

 of the hind-brain into the root- 

 - lets of the vagus and spinal ac- 



Fig. 3. Section of wall of hind-brain CeSSOry UCrveS (Fig. 3 VT.). That 

 through vagus rootlets. X 1^0. gc. germ thcSe CClls Wauder OUt in COU- 

 cells of His. ic. indifferent cells. »6. neuro- • j i i u „ „ 4. u^ 



blasts, vr. vagus rootlets. sidcrablc numbers can not be 





1) Abhandl. Math.-phys. Klasse d. Kgl. Sachs. Gesellsch. d. Wiss., 

 Bd. 8, Leipzig 1891. 



