20 WONDERS OF ORGANIC LIFE. 



a state of gentle but almost unceasing agitation, 

 by a peculiar motion of that organ, effected by 

 its muscular fibres. This vermicular motion is 

 termed peristaltic. The stomach, we may here 

 observe, is divided into two portions, a cardiac 

 portion, into which the gullet immediately 

 leads ; and a pyloric portion, which opens into 

 the commencement of the alimentary canal. 

 Now, the food when swallowed passes into the 

 cardiac portion ; and the stomach, which when 

 unemployed is one undivided bag, or sacculus, 

 as it is termed, contracts after the fashion of an 

 hour-glass, by the action of the circular fibres 

 of the muscular coat, thus forming two bags, or 

 sacculi, by far the largest of which is the car- 

 diac. Here the food awaits the dissolving 

 influence of the gastric juice. At this juncture 

 a remarkable change takes place in the lining 

 membrane of the stomach. When the stomach 

 is empty, this membrane is of a pale pink 

 colour ; but now it becomes of a bright red 

 colour, studded with innumerable minute lucid 

 points, from which a pure limpid and colourless 

 fluid distils, and mingling with the food effects 

 its gradual solution. This fluid is the gastric 

 juice, the true solvent of the food, and its action 

 is entirely chemical ; as the food is dissolved, 

 the reduced material is transmitted by means of 

 the peristaltic action of the muscular coat of 

 the stomach into the pyloric portion, where it 

 accumulates. This solution of the food is in no 

 respect analogous to that decomposition by pu- 

 trefaction which would be effected by the agency 



