PHYSIOLOGICAL ABSORPTION. 351 



In favour, perhaps, of the theory that fats must be split 

 before absorbed, is the fact that Nencki found the absence 

 of bile lessened the splitting power of the pancreatic juice, 

 and Munk finds that neutral fats are not so well absorbed 

 (by 6 per cent.) as free fatty acids by dogs with biliary 

 fistula. 



In fine, since the only histological observation of the 

 actual corpuscular theory of absorption of fat by the cells is 

 that of Thanhoffer, an observation which, we repeat, needs 

 confirmation, we must at present reserve judgment as to 

 whether the fats enter the cells in some form of solution, or 

 are actually " swallowed " in fine particles. The droplets, 

 once in the cells, are forwarded to their deeper ends, and 

 then discharged into the fluid filling the meshes of the villus 

 parenchyma. From here, probably, by the action of the 

 pressure produced by the villus-muscle, they are forced in 

 suspension through the wall of the lacteal, and this possibly 

 causes a finer division, for the " fett-staub " of the chyle is 

 composed of far finer particles than those seen within the 

 sponge of the villus. 



We can only understand the progress of the fat particles 

 within the cells as being produced by some kind of motion 

 analogous to "streaming movements " of protoplasm, but 

 this has not been definitely observed, unless perhaps by 

 Spina, in the cells lining the gut of the common house fly, 

 and when we come face to face with the ultimate cause of 

 that " physiological " absorptive action for fluids, spoken of 

 above, we can only imagine something of the same kind. 



Many have admitted active changes of shape of the 

 cylinder cells, but Spina's observations form the only in- 

 stance in which it has been definitely maintained that a 

 regular periodic change of shape is visible during an act of 

 absorption. 



The gut cells of fly maggots, especially when fed upon 

 frog's muscle stained with methyl violet, Spina maintains, 

 can be seen to swell at their free ends, suck up the violet 

 solution, and then contract and pass the solution towards the 

 body cavity. He says that these cells refuse to take up the 

 coloured solution from the body cavity and " secrete " it into 



