ABSORPTION. 



right side of the heart. The chyle, on the other hand, containing also 

 a large proportion of fatty ingredients, passes by the thoracic duct 

 directly to the left subclavian vein and is there mingled with the return- 

 ing current of the venous blood. But all these substances, after entering 

 the circulation and coming in contact with the organic ingredients of 

 the blood, are modified in such a way as no longer to be recognizable 

 under their original form. This change takes place very rapidly with 

 the albuminose and the sugar, both of which are taken up in greatest 

 proportion by the bloodvessels and are carried at once through the 

 hepatic capillaries. The albuminose passes, in all probability, into the 

 condition of ordinary albumen, while the sugar rapidly becomes decom- 

 posed, or transformed, and loses its characteristic properties ; so that, 

 on arriving at the entrance of the general circulation, both these newly 

 absorbed ingredients have become already assimilated to those which 

 previously existed in the blood. The fatty matters also, which reach 

 the blood on the right side of the heart both by the portal and hepatic 

 veins, and by the thoracic duct and subclavian vein, undergo a trans- 

 formation while passing through the lungs by which their distinctive 

 characters are destroyed, and they are no longer visible as oleaginous 

 molecules. This alteration is so complete, during the early part of 

 digestion, or when the proportion of fat in the food is small, that all the 

 oleaginous matter disappears in the lungs and none of it is to be de- 

 tected in the blood of the general circulation. 



But as digestion proceeds, especially when the food has been abun- 

 dant in oleaginous substances, an increasing quantity of fatty matter 

 finds its way, by these two passages, into the blood ; and a time at last 

 arrives when the whole of the fat so introduced is not destroyed during 

 its passage through the lungs. Its absorption taking place at this time 

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

 quantity, in the blood of the general circulation ; and, lastly, when the 

 intestinal absorption is at its point of greatest activity, it is found in 

 considerable abundance throughout the entire 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 circula- 

 tion, everywhere contains a superabundance of fat, derived from the 

 digestive process. If blood be then drawn from the veins or the arteries 

 in any part of the body, it will present the peculiar 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, the fatty substances 

 which it contains rise to the top and cover its surface with a partially 

 opaque and creamy-looking pellicle. This appearance has been occa- 

 sionally observed in the blood of the human subject, particularly in 

 cases of apoplexy occurring after a full meal. It is a purely normal / 

 phenomenon, and depends simply on the rapid absorption, at certain 

 periods during the digestive process, of oleaginous substances from the 

 intestine. It can be observed in the dog at any time by feeding him with 



