TISSUES OF THE BODY. 337 



delicate interlacement of nerves, woven, as it were, round the intestinal 

 tube (a), and having polyhedral meshes. 



At each nodal point in these there is always situated an aggregation of 

 ganglion cells (b), sometimes large, sometimes small, but usually causing 

 but a moderate thickening of the cord. Two adjacent ganglia, also, may 

 be connected by means of a band formed of cells, beside which form the 

 most characteristic examples of annular ganglia and commissures are also 

 to be met with. Though liable to variation to a certain extent, according to 

 the different species of animals, the whole formation is usually very much 

 flattened everywhere. Here again we also meet with smaller ganglionic 

 bodies, pale and very fine nerve fibres, and a nucleated perineurium, 

 beside which apolar cells are to be observed, with others giving off two or 

 three processes. 



From this plexus in question innumerable delicate nervous twigs are 

 sent off to the circular and longitudinal muscular fibres of the alimentary 

 canal, presiding over the peristaltic action of the latter. 



The genito-urinary apparatus, also, is no exception in the occurrence of 

 such small nervous knots. Thus they have been seen by Remak in the 



Fig. 323. From the small intestine of the Guinea pip (after Auerbach). a, nervous inter- 

 lacement ; 6, ganglia ; c, lymphatic vessels. 



bladder of the pig, and in other mammals by Meissner. In the same 

 organ of the frog they may be recognised with great ease also (Manz, Klels.} 



In the corpora cavernosa of the male organ of generation these knots 

 were found between the years 1830 and 1840 by /. Mutter. They are 

 also present in the nerves of the human and mammalian uterus, and in 

 the connective-tissue around the vagina, as well as in the submucosa of 

 the latter. 



Remak and Manz mention ganglionic plexuses around the muscular 

 gland-ducts of birds also. 



In the lachrymal and salivary glands of mammals, finally, therefore, 

 in organs which elaborate large quantities of secretion under nervous 

 stimulus, very complicated nervous networks of dark-edged fibres, richly 

 studded with ganglia, have been met with by Krause. 



