200 FUNCTIONS OF NUTRITION. 



blood was again allowed to pass, symptoms of general poisoning were 

 manifest. Lastly, in a third experiment, he removed the nerves and 

 lacteal vessels supplying the intestinal fold, leaving the blood-vessels 

 untouched. Hydrocyanic acid, introduced into the intestine, found an 

 immediate entrance into the general circulation, and the animal was at 

 once poisoned. The blood-vessels, therefore, are not only capable of 

 absorbing fluids from the intestine, but may take them up even more 

 rapidly than the lacteals. 



The entrance of digested materials into the blood-vessels of the intes- 

 tine is demonstrated in a similar way. After the digestion of food 

 containing albuminous and starchy ingredients, both glucose and pep- 

 tone are met with in the blood of the portal vein. Emulsioned fatty 

 matters may also be followed, in their passage through the same chan- 

 nels, by the chylous aspect which they communicate to the portal blood. 

 The blood of the portal system, in carnivorous animals, during diges- 

 tion, contains fatty matter in a state of minute subdivision, similar in 

 appearance to that found in the chyle and in the villi ; and these ingre- 

 dients are often so abundant as to cause a turbid appearance in the seruin 

 after coagulation. A variety of observers (Lehmann, Schultz, Simon), 

 in examining the blood from different parts of the body, have also 

 found the blood of the portal system considerably richer in fat than that 

 of the arteries or of other veins, particularly while digestion is going on. 



Absorption by the Lacteals. The absorption of digested materials, 

 particularly of the fatty matters, is also accomplished by the lacteals 

 of the small intestine. These vessels are part of the great lymphatic 

 system, which is distributed everywhere in the integuments of the 

 head, the parietes of the trunk, the limbs, and in the glands, muscles, 

 and mucous membranes throughout the body. Originating in the tis- 

 sues of these organs, they pass from the periphery toward the centre, 

 converging and uniting with each other like the veins, and passing, at 

 various points, through the lymphatic glands. 



The fluid generally contained in these vessels is the " lymph." It is 

 a colorless or slightly yellowish transparent liquid, absorbed by the 

 lymphatic vessels from the various tissues, and containing, beside water 

 and saline matters, a small quantity of fibrine and albumen. 



The lymphatic vessels of the intestine originate in the villi, as longi- 

 tudinal spaces lined with flattened epithelium cells, becoming provided, 

 after a short distance, with transparent, elastic coats, like those of the 

 capillary blood-vessels. On emerging from the villi they become part 

 of the lymphatic plexus, from which the main branches pass between 

 the layers of the mesentery, from the intestine toward the posterior 

 part of the abdomen. In this part of their course they inosculate with 

 each other by transverse branches, and pass through several ranges of 

 mesenteric glands, representing the lymphatic glands of the abdominal 

 cavity. Near the attached portion of the mesentery, on the right side 

 of the abdomen, about the level of the second lumbar vertebra, they 

 terminate in a saccular dilatation, the " receptaculum chyli." From this 



