ABSORPTION. 203 



rapidly than its decomposition, it begins to appear, in moderate 

 quantity, in the general circulation ; and, lastly, when absorption is 

 at the point of greatest activity, it is found in considerable abundance 

 throughout the vascular system. At this period, some hours after the 

 ingestion of food rich in oleaginous matters, the blood, not only of the 

 portal vein, but also of the general circulation, contains a superabun- 

 dance of molecular fat, derived from the digestive process. Blood drawn 

 at that time, from the veins or the arteries in any part of the body, will 

 present the appearance known as that of " chylous " or " milky " blood. 

 On the separation of the clot the serum is turbid ; and after a few hours 

 of repose, its fatty ingredients rise to the surface in an opaque, creamy- 

 looking pellicle. This appearance has been sometimes observed in 

 human blood, in cases of sudden death after a full meal. It is a purely 

 normal phenomenon, due to the rapid absorption, at certain periods 

 during digestion, of oleaginous substances from the intestine. It can 

 be observed at any time in the dog by feeding him with fat meat, and 

 drawing blood, seven or eight hours afterward, from the carotid artery 

 or the jugular vein. 



This condition lasts for a varying time, according to the amount of 

 oleaginous matter in the food. When digestion is terminated, and fat 

 ceases to be absorbed, its transformation continuing to take place in 

 the blood, it gradually disappears from the vascular system ; and, 

 finally, when the whole of it has been disposed of by the nutritive 

 process, the serum again becomes transparent, and the blood returns to 

 its ordinary condition. 



In this manner the nutritive elements of the food, prepared by the 

 digestive process, are taken into the circulation under the forms of 

 j>eptone, glucose, and chyle, and accumulate as such at certain times in 

 the blood. But these conditions are temporary and transitional. The 

 absorbed materials soon pass into other forms, and become assimilated 

 to the preexisting elements of the circulating fluid, thus accomplishing 

 finally the object of digestion, and replenishing the blood with its 

 nutritive elements. 



Absorption of Carbohydrates and Production of Glycogen 

 in the Liver. 



The absorption of starchy and saccharine matters, and the changes 

 which they undergo while passing through the liver to the general cir- 

 culation, have been the subject of extended observations, and require 

 a special description. They are connected with the production of 

 glycogen in the liver, as well as with its transformation and disappear- 

 ance. 



If the liver of a carnivorous or herbivorous animal, after twenty-- 

 four hours' fasting, be taken from the body immediately after death, 

 finely divided, and boiled for a few moments in water with animal 

 charcoal or an excess of sodium sulphate, to eliminate the albuminous 

 and coloring matters, the filtered fluid will be nearly clear, or will show 



