1902.] NATURAL SCIENCES OF PHILADELPHIA. 335 



support to their view ; while it is difficult to reconcile it with the 

 emulsion view. Pfluger (31) has used Heidenhain's figures to show 

 that fat does not appear in the striated border of mammalian epithelial 

 cells, and he declares, quoting Funke (32) and Will (33), that it has 

 never been so demonstrated except by Kolliker (34), who, as Pfluger 

 says, wanted to see fat particles to substantiate his theory that the striae 

 are pores. My own observations on this point in the isopods were 

 begun with the purpose, primarily, of demonstrating the pores in 

 the chitinous lining (see p. 310). It was hoped that if fat is 

 absorbed in the form of emulsion, it would blacken densely in the 

 intima after osmic acid. Consequently particular attention has 

 been given to this point. About twenty-five intestinef^ from ani- 

 mals in all stages of digestion, from four hours to 145 hours after 

 feeding, have been sectioned and each one examined carefully with 

 this point in view. In no case have I seen a single cell whose 

 intima contained demonstrable fat globules. (Note that in fig. 10, 

 Plate XVI, the intima is stained with acid-fuchsine. ) It has been 

 previously mentioned that the globules on the luminal side of the 

 cell are always small in size, while they increase gradually farther 

 up the cell. This is manifestly what is required by the solution 

 theory, as has been recognized by Funke, Will, Altmanu, Krehl (35), 

 Pfluger and others. If fat enters the cell in the form of fatty acid 

 and glycerine, or soap and glycerine, and these are then synthesized 

 into neutral fats under the influence of the cell, the neutral fat 

 would naturally appear first in small globules at the luminal edge, 

 and these would increase in size or in number, or both, the more 

 the products of digestion Avere brought under the synthesizing action. 



It cannot be denied, as urged by Heidenhain and others, 

 that if fat did enter the cell in the form of a fine emulsion, and 

 were then to fuse into larger globules, the same appearance might 

 be presented; but there is no assignable reason then why larger 

 globules are not formed in the membrane (intima of isopods) or 

 on the luminal side of the cell. In line with Will's results, it may 

 be remarked further that beef suet does not melt at the temperature 

 of the isopod body (about 25° C. ), and cannot therefore be emul- 

 sified. Hence the globules in fig. 19 must result from synthesis. 



On the question of what effects the revei*se action — the synthesis 

 of the products of digestion into neutral fats — I can do little more 

 than conjecture with others. Until recently no attempt has been 



