Diseases of Ihe J iilestiiies. 441 



surely possess sonic degree of influence inhibiting- the multipH- 

 cation of tlie inicro])hytes taken in with tlie food Marked ex- 

 cessive prevalenc<^ of l)acteria i.^, however, niainl\ ])revented by 

 the comparatively rapid passage of the chyme through the small 

 intestine and the discharge of large quantities of microorganisms 

 periodically with the dejecta from the large bowel in regular 

 defecation. 



Ir conditions which interfere with the normal passage of the 

 chvme through the intestinal tract, as in stagnation of the intes- 

 tinal contents from obstruction, strictures, etc., or where the 

 epithelium of the mucous membrane has undergone changes 

 (degeneration, necrosis, desquamation), even the ordinary in- 

 testinal bacteria are capable of causing harm ; and this is obvi- 

 ously possible where other types of microphytes having special 

 toxic properties are introduced, these perhaps causing epithelial 

 necroses or their toxic products being absorbed. We should re- 

 gard, at any rate, as harmful products of ordinary intestinal 

 bacteria the products of acid fermentation of the carbohydrates 

 (lactic acid, butyric acid, acetic acid), these when present in large 

 amount causing erosion of the mucous membrane (especially 

 the delicate mucous membranes of young individuals), and gases, 

 as hydrogen and methane and sulphuretted hydrogen, arising in 

 albumen putrefaction. 



The metabolic products of the bacteria themselves are even 

 more numerous and their influences varied. But little is known 

 of their relation with the pathology of the intestine, and 

 there is so nmch confusion as" to the nature of these some- 

 times poisonous su1)stances. and their relation to the alkaloids, 

 albuminates, enzymes, etc., that it is at present best to be satis- 

 fied with their tentative classification into toxines and endotoxines. 

 We can only speak in a general way of the bacterial processes in 

 the intestinal canal as the source of pathogenic and fatal changes, 

 and say that on the one hand they occasion local lesions like 

 inflammations, hcemorrhages or necroses, and on the other hand 

 give rise to general intoxications. Similar efifects may be pro- 

 duced bv the ingestion of various chemical substances (poisons 

 taken in with the food).- 



In many intestinal affections disturbances of the absorptive 

 power of the mucous meiubrane ensue. This is especially true 

 of the diffuse lesions ; although in circumscribed changes the 

 intervening portions of mucous membrane remaining unaltered 



