QUANTITY OF LYMPH AXD CHYLE. 363 



weight of their bodies as I : 7, the quantity of lymph daily 

 traversing the thoracic duct would appear to be about 

 equal to the quantity of blood at any time contained in the 

 animals. Schmidt's observations on foals have yielded 

 very similar results. By another series of experiments, 

 Bidder estimated that the quantity of lymph traversnfg 

 the thoracic duct of a dog in twenty-four hours is about 

 equal to two -thirds of the blood in the body. If we take 

 these estimates, it will not follow from them that the whole 

 of an animal's blood is daily replaced by the development 

 of lymph and chyle ; for even if the quantity of lymph 

 and chyle daily formed be equal to that of the blood, the 

 solid contents of the blood will be much too great to be 

 replaced by those of the lymph and chyle. According to 

 Nasse's analyses, the solid matter of a given quantity of 

 blood could not be replaced out of less than three or four 

 times the quantity of lymph and chyle. 



Absorption by the Lacteal Vessels. 



During the passage of the chyme along the whole tract 

 of the intestinal canal, its completely digested parts are 

 absorbed by the blood-vessels and lacteals distributed in 

 the mucous membrane. The blood-vessels appear to 

 absorb chiefly the dissolved portions of the food, and 

 these, including especially the albuminous and saccharine, 

 they imbibe without choice ; whatever can mix with the 

 blood passes into the vessels, as will be presently described. 

 But the lacteals appear to absorb only certain constituents 

 of the food, including particularly the fatty portions. The 

 absorption by both sets of vessels is carried on most 

 actively, but not exclusively, in the villi of the small intes- 

 tine; for in these minute processes, both the capillary 

 blood-vessels and the lacteals are brought almost into 

 contact with the intestinal contents. 



It has been already stated that the villi of the small 

 intestine (figs. Si and 82), are minute vascular processes 



