440 Disturbances of Digestion. 



of tlu' organ may ^ause it to be rapidly emplied into the intes- 

 tine, or. in association with the mnscles of respiration (spasmodic 

 contraction of the muscles of the abdominal wall and diaphragm), 

 may cause vomiting (■z'oiiiitiis) . It may be safely assumed that, 

 as in man, more or less gastric pain is caused also in animals by 

 various affections. Distension of the stomach, the marked stretch- 

 ing of the wall, give rise. to a sense of pressure: and the local 

 effects of poisons, of increased proportions of acid, and of toxic 

 bacterial products upon the sensory nerve fibres of the mucous 

 membrane, and especially the occurrence of spasms of the gastric 

 muscles, must surely often cause intense pain. It is known that 

 in man migraine and vertigo as well as epileptiform convulsions 

 may he of gastric origin,*- apparently from vagus irritation; and 

 some of the nervous symptom groups, as distemper of dogs, may 

 perhap> l:e expltiined by gastric changes. 



Diseases of the Intestines. — In all intestinal diseases the 

 micru-organisms, which teem in the contents and cause all sorts 

 of disintegrative changes in the material, play an important part. 

 Bacteria of many t_\pes, yeasts and hyphomycetes, as well as in- 

 fusoria, are to l)e found in the intestine of the healthy human be- 

 ing and animal, being introduced with the food. Pasteur and 

 Schottelius have pointed out that the presence of these corn- 

 mensualists is an absolute necessity for the herbiverous animal, 

 the bacterial processes being adjuvants in the digestion of the 

 food ( it has been impossible to keep alive chicks hatched in 

 sterile surroundings upon artificially sterilized food) ; although 

 young guinea pigs have shown their alnlitv to live and thrive on 

 pure milk diet without bacteria in llun- intestine (Thierfelder 

 and Xuttal). 



The harmlessness of the ordinary intestinal bacteria is due 

 to the fact that the healthy epithelium of the gastric and intestinal 

 mucous membrane acts as an impenetrable barrier against them; 

 the protective means possessed by these cells being apparently 

 their strongly acid, albumen precipitating nucleinic acids (Klem- 

 perer). Again it is possible that the intestinal epithelium, as well 

 as the rest of the tissue in every indivklual. may become accus- 

 tomed to the toxic products of the ordinary intestinal bac- 

 teria, just as the epithelium of the stomach and upper part 

 of the intestine is acid proof ; or it may be that an immunity 

 is obtained by the formation of antibodies. Then too the 

 acid gastric and small intestinal juice, as well as the bile, 



