

////: //;/>-// 1 /: .\rr.\i; ITVB i\ wi in/ i/./.i. 



tli. 'V constitute tin- sphincter (or pyloric valve) which envelops thut 

 orifice. 



The tli> /'/'me (Fig. 186, A), like the first, is specially drstinr.l t'<>i- 

 the left sac, and cannot be properly studied except in an everted stoumrh 

 deprived of its mucons membr.ine. Much thicker than the superficial plain-, 

 it yet, in its general arraiigeinent, much resembles it. Thus, its fasciculi 

 present loops which embrace the left </-</<-., and whose extremities are 

 l<i>t on the laces of the organ, where some of them b.-eome continuous \\ith 



185. 



Mlx'l I. All riliKlN or INI. MOM.VCIl; 



i MKKNAL AND MIDDLK LAYKRS. 

 A, Fibres of the external layer enveloping 

 the left sac ; u, Fibres of the middle plane 

 in the right sac ; C, Fibres of the ceso- 

 phagus. 



m:i;i- ASH .MIIUH.I: HUBCULAB LAYKH i.\- 



POSKD 11Y KKMOV1NG Till Ml>i;s MEM- 

 HI: AN K FROM AS EVKRTED STOMACH. 



A, Deep layer of fibres enveloping the left sac ; 



11, Fibres of the middle plane which alone 

 form the muscular layer of the right sac ; 

 c, Fibres of the oesophagus. 



the circular fibres. The loops nearest the oesophagus embrace the stomachal 

 opening of that canal like a cravat. It is to be remarked that the fibres 

 of this deep layer intersect those of the superficial plane ; the former 

 passing from the left to the right sac, in inclining downwards towards 

 the great curvature, while the latter are directed to the right and slightly 

 upwards. 



From this arrangement it results, as a glance at Figs. 185, 186 will show : 

 1, That the right sac has only a single muscular plane; 2, That, on the 

 contrary, the left sac has three, all of which concur in propelling the 

 aliment that has accumulated in the left or oesophageal compartment into 

 the right, or true stomach. 



3. Mucous membrane. Independently of the general characters notified 

 in the interior of the stomach, it has to be remarked that the gastric mucous 

 membrane is united to the preceding tunic by an expansion of connective 

 tissue ; though it adheres but feebly throughout the right sac, especially 

 towards the greater curvature, where it is thickest ; and that it has no ridges 

 in the left sac, though in the right they arc always present, even when the 

 organ is inflated. 



On the surface of this membrane are seen microscopical apertures (<///<.//'). 

 the orifices of the excretory ducts of glands; these are rare in the left sac, 



