78 



DIGESTION. 



the seat of the extraordinary irritability of the stomach. It con- 

 sists of strata of muscular fibres d , commonly divided into three 

 orders, one longitudinal and two circular (straight and oblique), 

 but running in so many directions that no exact account can be 

 given of their course. 



" The third is the chief membrane. It is usually termed nerv- 

 ous, but improperly, as it consists of condensed cellular membrane, 

 more lax on its surfaces, which are united, on the one hand, with 

 the muscular, and, on the other, with the internal villous coat. 

 It is firm and strong, and may be regarded as the basis of the 

 stomach. 



" The interior (besides the epithelium investing the whole ali- 

 mentary canal), improperly called villous, is extremely soft, and 

 in a manner spongy, porous, and folded into innumerable rugae , 

 so that its surface is more extensive than that of the other coats; 

 it exhibits very small cells f , somewhat similar to those larger cells 

 which are so beautiful in the reticulum of ruminants. 



" Its internal surface is covered with mucus, probably secreted 

 in the muciparous crypts which are very distinct about the pylorus. 



" The stomach is amply furnished with nerves ? from each 

 nervous system, whence its great sensibility, owing to which it is 

 so readily affected by all kinds of stimuli, whether external, as 

 cold, or internal, as food and its own fluids, or mental; whence 

 also the great and surprising sympathy between it and most 

 functions of the system ; to which sympathy are referable the 

 influence of all passions upon the stomach, and of the healthy 

 condition of the stomach upon the tranquillity of the mind. h 



" The abundance and utility of the blood-vessels of the sto- 

 mach are no less striking. Its arteries, ramifying infinitely upon 

 the cellular membrane and glands, secrete the gastric juice, which 

 would appear to stream continually from the inner surface of the 

 stomach. 1 



" In its general composition this fluid is analogous to the saliva 



" Besides Haller, consult Berlin, Mem. de VAcad. des Sc. de Paris, 1761." 

 " Ruysch, Thes. Anat. ii. tab. v. fig. 2, 3, 4*." 

 " See G. Fordyce, On the Digestion of Food, p. 12. 59. 191." 

 " Walter, Tab. Nervor.. Thorac. et Abd<,m. tab. iv." 



" J. H. Rahn, Mirum inter Caput et Viscera Abdominis Commercium. Get- 

 ting. 1771. 4to. 



Dit. Vegens, De Sympathia inter Ventriculum et Caput. LB. 1784. 4to. 

 Wrisberg, Commentat. Societ. Sdentiar. Gotting. t. xvi." 

 1 " Ever. Home, Phil. Trans. 1817. p. 347. tab. xviii. xix." 



