724 INTERNAL SECRETIONS AND PRESERVATION OF LIFE. 



too small to account for the amount of fat absorbed. But it 

 seems to us that, if these only transfer the fat from the epi- 

 thelial cells to the lacteals, the to-and-fro excursions of each 

 cell and the enormous number of villi over which the food of a 

 single meal has. to pass amply compensate for the apparent 

 paucity of cells. An additional reason adduced by Professor 

 Foster is the fact that the administration of a saline such as 

 magnesium sulphate "produces effects the very reverse of ab- 

 sorption," these cells being present in unusual numbers. As 

 interpreted from our standpoint, and as will be shown when 

 the action of purgatives- is studied, these agents greatly increase 

 the flow of serum into the intestinal canal by reflex action and 

 crowd its walls with defensive agencies, including leucocytes. 

 We are dealing here, not with a normal process, such as is the 

 fat-absorbing function, but with an engorgement by protective 

 elements. 



The axial contraction and relaxation which occurs in the 

 villus to cause its various contents to gravitate into their re- 

 spective channels may, however, be instrumental in causing fat- 

 particles that have already passed the epithelium to enter, not 

 only the lacteal, but the venules also, fat-globules, or what pur- 

 ported to be such, having been found in the blood. This feat- 

 ure, and the manner in which fat-globules reach the general 

 lymphatic circulation, are exemplified in the following lines by 

 Stewart: "The contraction of the smooth muscular fibers of 

 the villus and the peristaltic movements of the intestinal walls 

 alter the capacity of the lacteal chamber, and so alternately 

 fill it from the lymph of the adenoid reticulum and empty it 

 into the lymphatic vessel with which it is connected. By this 

 kind of pumping action the passage of fat and other substances 

 into the lymphatics is aided. In the dog no fat is absorbed 

 by the blood-vessels, except perhaps a small quantity in the 

 form of soaps; it nearly all goes into the lacteals, and thence 

 by the general lymph-stream through the thoracic duct into 

 the blood." 



An interesting feature now asserts itself. Again are all 

 the basophiles poured into a channel, the left subclavian vein, 

 which empties into a large venous trunk, the superior vena 

 cava, which in turn carries them to the right heart. We have 



