288 ABSORPTION-LYMPH AND CHYLE. 



trogen from the air ; and the absorption of any thing else by these surfaces 

 is unnatural and generally deleterious. 



Absorption from Closed Cavities, Reservoirs of Glands, etc. Facts in 

 pathology, showing absorption from closed cavities, the areolar tissue, the 

 muscular and nervous tissues, the conjunctiva and other parts, are sufficient- 

 ly well known. In cases of effusion of serum into the pleural, peritoneal, per- 

 icardial or synovia! cavities, in which recovery takes place, the liquid becomes 

 absorbed. It has been shown by experiment that warm water injected into 

 these cavities is disposed of in the same way. Effusions into the areolar tis- 

 sue are generally removed by absorption. In cases of penetration of air into 

 the pleura or the general areolar tissue, absorption likewise takes place ; show- 

 ing that gases may be taken up in this way as well as liquids. Effusions of 

 blood beneath the skin or the conjunctiva or in the muscular or nervous tis- 

 sue may become entirely or in part absorbed. It is true that these are path- 

 ological conditions, but in the closed cavities, the processes of exhalation and 

 absorption are constantly going on, although not very actively. As regards 

 absorption from the areolar tissue, the administration of remedies by the hy- 

 podermatic method is a familiar evidence of the facility with which soluble 

 substances are taken into the blood, when introduced beneath the skin. 



Under some conditions, absorption takes place from the reservoirs of the 

 various glands, the watery portions of the secretions being generally taken 

 up, leaving the solid and the organic matters. It is supposed that the bile 

 becomes somewhat inspissated when it has remained for a time in the gall- 

 bladder, even when the natural flow of the secretion is not interrupted. Cer- 

 tainly, when the duct is in any way obstructed, absorption of a portion of the 

 bile takes place, as is shown by coloration of the conjunctiva and even of the 

 general surface. The serum of the blood, under these conditions, is always 

 strongly colored with bile. It is probable, also, that some of the watery por- 

 tions of the urine are reabsorbed by the mucous membrane of the urinary 

 bladder when the urine has been long confined in its cavity, although this 

 reabsorption is ordinarily very slight. Absorption may take place from the 

 ducts and the parenchyma of glands, although this occurs chiefly when for- 

 eign substances have been injected into these parts. 



ABSORPTION OF FATS AND INSOLUBLE SUBSTANCES. 



The general proposition that all substances capable of being absorbed are 

 soluble in water or in the digestive fluids must be modified in the case of the fats. 

 These are never dissolved in any considerable quantity in digestion, the only 

 change which they undergo being a minute subdivision in the form of a very 

 fine emulsion. In this condition the fats are taken up by the lacteals and 

 may be absorbed in small quantity by the blood-vessels. 



In studying the mechanism of the penetration of fatty particles into the 

 intestinal villi, it has been ascertained that the epithelial cells covering the 

 villi play an important part in this process. During the digestion of fat, 

 these cells become filled with fatty granules (Goodsir). Funke, in his atlas of 

 physiological chemistry, figures the appearances of the intestinal epithelium 



