620 DIGESTION. 



they do not correspond with what he says relating to the carbonic acid; 

 the quantity of which, according to him, goes on decreasing from the 

 stomach to the rectum. The analyses of MM. Magendie and Chevreul 

 show, that the proportion instead of decreasing, increases. Concerning 

 the origin of these gases, the remarks made on those in the small intes- 

 tine are equally applicable here. 



When the faecal matter has accumulated to the necessary extent in 

 the rectum, its expulsion follows; and to this function the term defeca- 

 tion has been assigned. The faeces collect gradually in the large intes- 

 tine, without any consciousness on the part of the individual. Sooner 

 or later, the desire or want to evacuate them arises. This is usually 

 classed among the internal sensations or desires. It is, however, of a 

 mixed character. It is not always in a ratio with the quantity of fcsces 

 as is shown by the fact, that occasionally the intestine is filled without 

 the want arising; and, if they be unusually thin or irritating, the desire 

 is developed, when an extremely small quantity is present, as in cases 

 of tenesmus. The period, at which the desire returns, is variable, 

 according to the amount and character of the food employed, as well as 

 the habit of the individual. Whilst the generality of persons evacuate 

 the bowels at least once a-day, and this at a period often regulated 

 by custom, others pass a week or two without any alvine discharge, 

 and yet may be in perfect health. Nay, some of the collectors of rare 

 cases 1 have affirmed, on the authority of Rhodius, Panarolus, Salmuth, 

 and others, that persons may remain in health, with the bowels moved 

 not oftener than once a month, three months, half a year, two years, 

 and even seven years! Sir Everard Home 2 refers to the case of General 

 Grose, who was in the Dutch service, under the Duke of Cumberland, 

 in the Flanders war; and who for thirty years had no passage through 

 the bowels. General Gage noticed that he ate heartily; but in two 

 hours left the table and rejected his meal. He was healthy, and capa- 

 ble of exercise like other men. Dr. Heberden 3 mentions the case of a 

 person, who had naturally an evacuation once a month only; and an- 

 other who had twelve evacuations every day during thirty years, and 

 then seven every day for seven years, and grew fat rather than other- 

 wise. A young lady referred to by M. Pouteau, 4 had no evacuation for 

 upwards of eight years ; although during the last year she ate abundantly 

 of fruit, and drank coffee, milk, tea, and broth with yolks of eggs; but 

 she had copious greasy sweats; and many similar extraordinary cases 

 have been recorded by Dr. Chapman 5 of Philadelphia. When the desire 

 to evacuate has once occurred, it generally persists until the faeces are 

 expelled. Sometimes, however, it disappears and recurs at an uncertain 

 interval ; and, if again resisted, may become the source of pain, and 

 ultimately command implicit obedience. That the pressure and irrita- 

 tion of the faeces develope the sensation is evidenced by the fact, that 

 the momentary relief experienced at times, when the desire is urgent, 



1 Art. Cas Rares, in Diet, des Sciences Mdicales. 



2 Lect. on Comp. Anat., v. 12, Lond., 1828. 3 Commentarii, p. 14. 



4 CEuvres Posthumes, i. 27, Paris, 1783. 



5 Lectures on the more important Diseases of the Thoracic and Abdominal Viscera, 

 p. 294, Philad., 1844. 



