CHAP, i.] TISSUES AND MECHANISMS OF DIGESTION. 517 



are B66D in the cubical cells of tin- glands of Lieberkiihn we infer 

 that those have nothing to do with the absorption of fat. 



How the fat enters into the substance of the cell we do not 

 know. We may presume that the striated border plays some part, 

 but what part we do not know. Though, as we have seen, the rods 

 making up the border appear able to move, to change their form, 

 we have no evidence that the fat is introduced into the cells by 

 means of any movements of these rods. We may imagine that the 

 globules pass into the cell substance by help in some way of these 

 rods, through amoeboid movements comparable with the ingestive 

 movements of the body of an amoeba; but we have no positive 

 evidence to support this view. We said ( 247) that bile promotes 

 the passage of fat through membranes, possibly by in some way 

 promoting a closer contact between the particles of fat and the 

 substance of the membrane ; but even if bile has this effect on the 

 surface of the cells, its action in this respect can be subsidiary only. 



Within the columnar cell the fat may be seen, both in osmic 

 acid preparations, and in fresh living cells, to be disposed in 

 globules of various sizes, some large and some small, each globule 

 placed in a space of the protoplasmic cell substance. It does not 

 follow that the fat actually entered the cell exactly in the form of 

 these globules ; it may be that the fat passes the striated border 

 in very minute spherules which, reaching the body of the cell, 

 run together into larger globules ; but whether this is so or not 

 we do not know. 



From the columnar cell the fat passes into the spaces of the 

 reticular tissue of the villus. It has, it is true, been contended 

 that it passes along the substance of the bars of the reticulum ; 

 but in carefully prepared osmic acid specimens of a villus in active 

 digestion of fatty food, the fat may be distinctly recognized as 

 largely filling up, still in the form of globules of various sizes, the 

 spaces in the meshes of the reticulum which are not occupied by 

 the leucocytes or allied wandering cells. We have seen ( 260) 

 that the bases of the columnar cells, through the gaps in the 

 basement membrane, directly abut upon the labyrinth of spaces ; 

 and the fat once out of the base of the cell is free in the 

 spaces of this labyrinth. How it issues from the cell we do not! 

 exactly know : possibly by a process analogous to the excretion of 

 solid matters by an amoeba. 



From the labyrinth of spaces of the reticulum of the villus the 

 fat passes into the cavity of the lacteal radicle ; and it is worthy ' 

 of note that in the passage it undergoes a change. In the interior 

 of the intestine, in the substance of the columnar cell, and ap- 

 parently in the labyrinth of the reticulum it is simply emulsified 

 fat consisting of globules small and large ; within the lacteal radicle 

 it consists partly of the same easily recognized globules but partly 

 of the extremely divided ' molecular basis ' ( 299) ; it is now no 

 longer emulsified fat but chyle. How and by what means this 



