336 



MANUAL OF HISTOLOGY. 



stance of both ventricles and auricles (Remdk). The most carefully studied 

 have been those of the frog, where they are situated in the septum between 



the auricles, and at the union 

 of the latter with the ven- 

 tricles. They are said only 

 to contain unipolar cells. 



These ganglionic plexuses 

 are also encountered in great 

 abundance in the walls of the 

 alimentary canal. Here at- 

 tention was first directed to 

 them by a discovery ofMeiss- 

 ner's, which initiated a series 

 of further investigations. 



The first of these gangli- 

 onic and nervous plexuses 

 extends in the human 

 and mammalian intestine 

 from the stomach downwards 

 through the submucosa. Its 

 peripheral branches probably 

 contain, for the most part, 

 motor elements for the mus- 

 cularis mucosce and some few 

 sensible fibres for the mucous membrane. 



This submucous ganglion plexus, as seen in the infant (figs. 326 and 

 322, 1), has narrow meshes, but in the adult broader and more irregular 

 ones. The number of twigs given off from it is variable (fig. 321, t>\ 



and the ganglia differ also 

 greatly as to size and 

 shape (fig. 321, a; 322, 

 1, a}. The smaller cells 

 of the latter are entangled 

 in the meshes of a nuc- 

 leated perineurium which 

 clothes (fig. 321, &/ 322, 

 c) likewise the efferent 

 trunks and commissures, 

 consisting of fine pale 

 nerve fibres (322, 2). 

 These cells are said to be 

 unipolar, apolar, and bipo- 

 lar : multipolar do not 



Fig. 322. -1. A large ganglion from the small intestine of a a PP ear to exist here, 

 suckling ten days old. a, ganglion with its cells; 6, c. efferent 

 nervous trunks with pale nucleated fibres in a fresh state. 2. 

 Small nervous twig of the same nature from a boy five years of 

 age, showing three primitive fibres. After treatment with 



Fig. 321. A ganglion from the submucosa of the smalt 

 intestine of a suckling ten days old. , ganglion; 6, 

 nervous twigs given off by the latter; e, injected capil- 

 lary network. This preparation had been macerated for 

 a very long period in pyroligneous acid. 



pyroligneous acid. 



Internally, this gang- 

 lion plexus gives off twigs 

 to the muscular coat of 

 the alimentary canal. 



Here, between the circular and longitudinal layers of the latter, a second 

 nervous apparatus, no less remarkable, is to be found namely, the so- 

 called plexus myentericus (fig. 323), for the discovery of which we are 

 indebted to Auerbach. 



Reaching from the pylorus to the rectum, it is seen as a regular and 



