546 ABSORPTION OF FAT. [BOOK n. 



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 

 extremely minute division of the globular fat into the ' molecular 

 basis ' takes place we do not know ; nor do we know the exact 

 manner in which the fat passes from the spaces of the reticulum 

 into the interior of the radicle. If the sheet of sinuous epithelioid 

 plates which forms the sole wall of the chamber is discontinuous, 

 presenting here and there gaps between the plates, the passage 

 presents no difficulty in itself, but does raise the difficulty why 

 there is so great a difference between the chyle inside the chamber 

 and the fat outside. On the other hand, if as observations seem to 

 shew the lining in question is actually continuous, the fat must pass 

 into the lacteal radicle either through the substance of the plates 

 or through the junction lines of cement. Such a passage presents 

 difficulties ; but at the same time we can conceive that the forces 

 which bring about the passage might convert some of the fat into 

 the molecular basis. 



We may here perhaps remark that the contents of the lacteal 

 radicle consist not exclusively of fat, but of fat accompanied by 

 the proteid and other substances which go to make up the chyle. 

 Proteid and other substances besides fat are also present in the 

 lymph which occupies in part the labyrinth of the body of the 

 villus, and are derived, like the lymph elsewhere, from the blood 

 of adjacent capillaries; at least, they are in part so derived, 

 though it may be not wholly, for as we have just seen the passage 

 of proteid material from the intestine into the substance of the 

 villus past the capillaries though not proved, must still be con- 

 sidered as possible. 



We have seen ( 262) that the spaces of the reticulum of the 



