242 ALBERT CUNTZ 



eluded, therefore, that the ganglia of the cardiac plexus are com- 

 posed exclusively of cells which have migrated thither from the 

 sympathetic trunks. 



The above observations prove conclusively that the earliest 

 anlagen of the cardiac plexus in the pig arise from cells which 

 migrate thither from the vagus trunks. This is probably true 

 for all mammals. In the human embryo of His, Jr., referred to 

 above, the cardiac plexus already had fibrous connections with 

 both the vagi and the sympathetic trunks. The anlagen of the 

 cardiac plexus would probably have been found considerably 

 earlier. 



My observations on the later development of the cardiac plexus 

 in the pig do not differ essentially from those of His, Jr., 3 on the 

 human embryo, except that the earliest cardiac nerves having 

 their origin in the sympathetic trunks are less intimately asso- 

 ciated with the vagi, and enter the cardiac plexus independently. 

 This fact was also observed by His, Jr., in embryos of the cat. 



(e) Cell migration along the vagi. — In sections taken at right 

 angles to the axis of the trunk, in the head region of embryos 9 

 or 10 mm. in length, medullary cells may be observed migrating 

 from the walls of the hind-brain into the rootlets of the vagus and 

 the spinal accessory nerves (fig. 15, c.m.vag.r.). That these 

 cells wander out in considerable numbers cannot be doubted. 

 In many sections medullary cells are observed drawn out into cone- 

 shaped heaps in the nerve-rootlets as they traverse the marginal 

 veil. Occasionally one of these cells is observed half in and half 

 out of the neural tube, and many are present in the nerve-rootlets 

 just outside the external limiting membrane. 



In sagittal sections the entire vagus trunk is seen to contain 

 many of these " accompanying" cells which are apparently mi- 

 grating peripherally. The ganglion of the trunk is, at this stage, 

 a somewhat irregular oval or elliptical body which is not sharply 

 limited distally. Cells appear to become separated from its dis- 

 tal end and to wander peripherally along the vagus trunk. Mi- 



3 Abhdl. Math-physischen Classe d. Konigl. Sachs. Gesell. d. Wiss. Bd. 8, Leipzig 

 1891. 



