258 ABSORPTION LYMPH AND CHYLE 



per cent of cane-sugar in water, which is only about one-fifth of a 

 normal solution. Physicists are still unacquainted with the cause of 

 osmosis; and while the bearing of the prevailing theories of osmotic 

 pressure, electrolysis and dissociation into anions and cations on absorp- 

 tion, nutrition and secretion are undoubtedly of the highest physiological 

 importance, this is not yet entirely clear. 



In no experiments performed out of the body, can the conditions 

 favorable to the passage of liquids through membranes in accordance 

 with purely physical laws be realized as they exist in the living organism. 

 The great extent of the absorbing surfaces ; the delicacy and permea- 

 bility of the membranes ; the rapidity with which substances are carried 

 on by the torrent of the circulation, so soon as they pass through these 

 membranes ; the uniformity of the pressure, notwithstanding the pene- 

 tration of liquids, all these favor the physical phenomena of absorption 

 in a way that can not be imitated in artificially-constructed apparatus. 

 Within the bloodvessels albuminous matters exist in a form that does 

 not permit them to pass through membranes, while the peptones are 

 highly osmotic. The sugars, also, pass through the walls of the ves- 

 sels with facility, as well as various salts and medicinal substances in 

 solution. The fats, as has been stated, pass mainly into the lacteals, 

 by a process already described, which can not be fully explained by the 

 laws of osmosis. 



LYMPH AND CHYLE 



It is estimated that the total quantity of lymph and chyle produced 

 in the twenty-four hours in a man weighing one hundred and forty-three 

 pounds (65 kilograms) is about 6.6 pounds (3000 grams). Reasoning 

 from experiments made on dogs thirteen hours after feeding, when the 

 liquid which passes up the thoracic duct may be assumed to be pure 

 unmixed lymph, the total quantity of lymph alone, produced in the 

 twenty-four hours by a man of ordinary weight, would be about 4.4 

 pounds (2000 grams). These estimates can be accepted only as 

 approximate, and they do not indicate the entire quantity of lymph 

 actually contained in the organism. 



There are no very satisfactory recent researches in regard to the 

 physiological variations in the quantity of lymph. In comparing the 

 quantity of liquid in the lymphatics of the neck in dogs, during digestion 

 and absorption, with the quantity which they contained soon after diges- 

 tion was completed, it has been found that while digestion and absorption 

 were going on actively, the vessels of the neck contained scarcely any 

 liquid ; but the quantity gradually increased after these processes were 

 completed (Collard de Martigny). 



