2d. The habit of continual spitting, which attends the chewing of tobacco and gums, and other substances, between meals, induces debility, not only of the salivary glands, but of the system generally. 436. _One secretory organ may do the office of another._ This increased action of a secretory organ may be sustained for a limited time without permanent injury, but, if long continued, a diseased action of the organ will follow. Of morbid secretions we have examples in the ossification of the valves of the heart, cancerous and other tumors. -=-=-=-=-=-=-=-=-=-=-=-= 434. What is the effect of impure blood on the secretory organs? 435. What results from stimulating excessively a secretory organ? How is this illustrated? 436. What is the effect when one secretory organ performs the office of another? -=-=-=-=-=-=-=-=-=-=-=-= _Observation._ In the evenings of the warm season, a chill upon the impressible skin, that suppresses the perspiration, is frequently followed by a diarrhoea, dysentery, or cholera morbus. These can be prevented by avoiding the chill. An efficient means of relief, is immediately to restore the skin to its proper action. 437. _The secretions are much influenced by the mind._ How this is effected, it is difficult to explain; but many facts corroborate it. Every one has felt an increased action of the tear-glands from distressing feelings. Cheerfulness of disposition and serenity of the passions are peculiarly favorable to the proper performance of the secretory function. From this we may learn how important it is to avoid such things as distract, agitate, or harass us. _Observation._ In fevers and other diseases, when the skin, mouth, and throat are dry from a suppression of the secretions, let the mind of the patient be changed from despondency to hope, and the skin and the membrane that lines the mouth and throat will exhibit a more moist condition, together with a general improvement of the vital organs of the system. Consequently, all just encouragement of the restoration to health should be given to a sick person. -=-=-=-=-=-=-=-=-=-=-=-= Give examples of morbid secretions. What is one cause of dysentery and cholera morbus? How can these affections he relieved? 437. Show the influence of the mind on the secretions. Mention instances of its influence. -=-=-=-=-=-=-=-=-=-=-=-= CHAPTER XXII. NUTRITION. 438. NUTRITION is the vital act by which the different parts of the body renew the materials of which they are composed. Digestion, circulation, absorption, and respiration, are but separate links in the chain of nutrition, which would be destroyed by the absence of any one of them.