110 THE FEEDING OF ANIMALS 



pancreatic juice when poured into the small intestine, but 

 that this enzym is formed from a mother substance in the 

 pancreatic juice (trypsinogen) after it comes in contact 

 with the intestinal juice, this result being accomplished 

 through the action of a body probably secreted from 

 the intestinal walls and called by Pawlow "enterokinase." 

 (See Par. 154.) 



158. Intestinal bacteria. So far, in presenting the 

 relation of ferments to digestion, only the unorganized 

 ferments or enzyms have been considered. While these 

 are chiefly concerned in normal digestion, organized 

 ferments are present throughout the entire intestinal 

 canal and play a part in food changes. They are very 

 abundant and active in the rumen and large intestine. 

 They act upon the proteins, causing putrefaction, dissolve 

 cellulose, and cause a decomposition of the carbohydrates. 

 The products of these fermentations include, among other 

 compounds, indol and skatol, which have the character- 

 istic fecal odor, volatile fatty acids, and gases, some of 

 which are carbon dioxid, hydrogen, marsh gas and hydro- 

 gen sulfide:' -The evolution of these gases appears to occur 

 constantly and normally with farm animals, particularly 

 the bovines, the quantity depending somewhat upon the 

 kind of food. (See Par. 127.) 



159. Effects of intestinal fermentations. Under cer- 

 tain conditions, fermentations of this character, which 

 are in part normal and may be beneficial, proceed so 

 far as to be deleterious. Gorging with a very succulent 

 food, such as immature clover, after a period of dry 

 foods, or anything which retards digestion, such as 

 imperfect mastication, excessive eating, and failure of the 

 organs secreting the digestive fluids to supply these fluids 

 in sufficient abundance, give these bacteria a better oppor- 



