336 SCIENCE PROGRESS. 



blood is concerned, two ways are open, through the 

 protoplasm of the cells themselves, or through the 

 cement substance between these structures. The ubi- 

 quitous leucocyte is present in the fluid filling the fine con- 

 nective tissue sponge work of the body of the villus, and 

 may mount in the soft cement between the surface cells 

 and gain the gut surface. Especially in hunger and 

 hibernation do they pass between the epithelial cells. 

 The oxyphil variety is very frequent, and is most 

 numerous, and contains most granules during digestion. 

 Large conglomerate macrophages also abound, holding the 

 remains of effete cells and micro-organisms. 



It will be well at first to confine our attention to the 

 consideration of the absorption of water, and of substances 

 soluble in water which occur in the intestine, viz., salts, 

 sugars, and albuminous bodies. 



The older ideas of the absorption of fluids were Imbibi- 

 tion (Rudolphi and Magendie), Osmose (Dutrochet) and 

 Filtration (Briicke), and the merit of first definitely doubting 

 the sufficiency of the two latter processes, to explain the 

 phenomena of absorption in the gut, is due, probably, to 

 Hoppe Seyler. 



Hoppe Seyler pointed out that filtration, under peri- 

 staltic pressure, and such pressure is never great, cannot be 

 of much value in moving the contents of the gut through 

 its walls, on account of the plasticity of the latter, and, more- 

 over, against the osmotic theory he advanced the fact that 

 weak alcohol in the gut causes no outpouring of water from 

 the blood, but the whole solution is quickly absorbed. He 

 considers that " Bewegungs-vorgange in den Zellen " are the 

 cause of absorption, and instances the choleraic patient with 

 shed epithelium, whose absorption is at a standstill. It 

 must, however, be stated that Johannes Miiller had the idea 

 of the action of the cell long before, for he speaks of it as 

 exerting an " organische Anziehung ". 



We have many cases in which it has been shown that 

 the diffusion of solutions does not take place with equal ease 

 in living and dead membranes. Claude Bernard found 

 curare passed with greater difficulty across the living than 



