264 UNCONSCIOUS NERVOUS OPERATIONS 



matter once separated from the blood for rejection is a 

 danger to be guarded against. 



388. Attention has already been called to some of the 

 ways* by which man is protected from the injurious prod- 

 ucts of his own organism ( 335, 336, 338). The gastric 

 juice contains more than enough hydrochloric acid to 

 prevent all fermentation in the stomach ; but in the 

 intestines its action is neutralized by the alkalis of the 

 intestinal juices. In the intestines a variety of poisons 

 are found, and when digestion is disordered the num- 

 ber and quantity may be dangerously increased. Some 

 of these are excreted, while others are absorbed into the 

 blood. The liver is the great defense against the poisons 

 in the blood, many of which are caught by that gland, 

 and either transformed or passed on to be removed from 

 the body by means of the kidneys. By the lungs 

 enough carbon dioxide is removed from the body every 

 day to poison a man to death many times over ; but other 

 injurious matters are found in expired air, especially in 

 the case of persons suffering from defective nutrition. 

 The skin also plays its part in the elimination of poisons, 

 and the peculiar odor of the perspiration in certain abnor- 

 mal conditions is a guide to the physician as to the 

 internal state of the system. 



All these facts show the immense importance of keep- 

 ing constantly open and in healthy condition the various 

 channels of excretion. 



389. Influence of Alcohol upon Excretion. If the waste 

 substances constantly formed in the body are not promptly 

 removed, they tend to poison the system. When the or- 

 ganism is at a high level of health, the breaking down of 

 tissue by oxidation, which produces waste, goes on rapidly 

 and vigorously. When this is retarded, as we have seen 



