88 AGRICULTURE. [en. 



saliva must not be regarded simply as water which 

 moistens the food, for it has the power of converting 

 the starch of food into sugar. This~chen;ical change 

 is commenced whilst the food is in the first stomach, 

 and it is materially advanced under the process of 

 mastication. 



184. The food therefore having been gathered in, 

 softened and fully masticated, when it has thus become 

 sufficiently soft and sweetened, it is passed into the 

 third stomach. In the third stomach the food is 

 simply allowed to macerate or soak for a time, and it 

 is probable that the starchy matter of the food is here 

 more completely changed into sugar. The softened 

 and sweetened food which is now a semi-fluid mass, is 

 passed on after a time into the fourth stomach for 

 further preparation. The first stage is now complete, 

 for the food has been finely broken up, softened, 

 and its starchy matter largely turned into 

 sugar. 



185. In the fourth stomach, we find that the 

 membrane which lines it, has the power of pouring 

 out, like perspiration on the skin, a liquid which has 

 been named gastric juice. It is a clear colour- 

 less liquid, but with an acid taste, arising from the 

 presence of hydrochloric and lactic acids. It also 

 contains a peculiar organic compound named rjepsin. 

 The gastricjuice has a very strong power of^ssplvmg 

 the nitrogenous portions of the food, and through its 

 influence"" the food"~undergoes this further change. 

 The semi-fluid mass is at this stage called the chyme. 

 This is the second stage in the process of digestion, 

 and the chyme therefore represents, the original food 

 softened, finely divided, with its starchy matter turned 

 into sugar, and the nitrogenous portions of the 

 food brought into solution. 



1 86. Another stage has to be accomplished, for 

 in the chyme we have the fatty matter still floating 

 about as oil, and this has to be prepared for being 



