DIGESTION. 137 



During digestion the exit of the food from the stomach 

 into the intestine is prevented by the pylorus being closed 

 by the action of its sphincter muscle. It is clear that the 

 food is required to remain for some time in the stomach in 

 order to be perfectly digested, and this closing of the j)ylo- 

 rus appears to be one means employed for attaining this 

 end; and another is derived from the property which the 

 gastric juice possesses of coagulating, or rendering solid, 

 every animal or vegetable fluid susceptible of undergoing 

 that change. This is the case with fluid albumen; the white 

 of an egg, for instance, which is nearly pure albumen, is 

 very speedily coagulated when taken into the stomach; the 

 same change occurs in milk, which is immediately curdled 

 by the juices that are there secreted, and these efi^ects take 

 place quite independently of any acid that may be present. 

 The object of this change from fluid to solid appears to be 

 to detain the food for some time in the stomach, and thus 

 to allow of its being thoroughly acted upon by the digestive 

 powers of that organ. Those fluids which pass quickly 

 through the stomach, and thereby escape its chemical ac- 

 tion, however much they may be in themselves nutritious, 

 are very imperfectly digested, and consequently afibrd very 

 little nourishment. This is the case with oils, with jelly, 

 and with all food that is much diluted.* Hunter ascertained 



* A diet consisting" of too large a proportion of liquids, although it may 

 contain much nutritive matter, yet if it be incapable of being coagulated by 

 the stomach, will not be sufficiently acted upon by that organ to be proper- 

 ly digested, and will not only afford comparatively little nourishment, but be 

 very liable to produce disorder of the alimentary canal. Thus, soups will 

 not prove so nutritive when taken alone, as when they are united with a 

 certain proportion of solid food, capable of being detained in the stomach, 

 during a time sufficiently long to allow of the whole undergoing the pro- 

 cess of digestion. I was led to this conclusion, not only from theory, but 

 from actual observation of what took place among the prisoners in the Mil- 

 bank Penitentiary, in 1823, when on the occasion of the extensive preva- 

 lence of scorbutic dysentery in that prison, Dr. P. M. Latham and myself 

 were appointed to attend the sick, and inquire into the origin of the disease. 

 Among the causes which concurred to produce this formidable malady, one 

 of the most prominent appeared to be an impoverished diet, consisting of a 

 Vol. II. 18 



