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an entirely different conception of the process of resorption. 

 C o h n h e i m considers the gut wall merely as a diffusion-mem- 

 brane through which substances pass equally well in both 

 directions. There is no ..polarity" ; there are no substances 

 which are resorbed against an osmotic difference. On the 

 other hand there is an active water-resorption, „die sich 

 aus den osmotischen Kraften allein nicht erklaren lasst". The 

 diffusion of dissolved substances takes place just as in every 

 diffusion membrane, without any „ orientation", but water is 

 resorbed quite independently and simultaneously. 



Enriques pictures the process of resorption in an entirely 

 different way. very much as it takes place in mammals where 

 this remarkable, and as yet physically unintelligible process was 

 discovered by Cohnheim (Zschr. f. Biol. 36. 1898. 129 and 

 37. 1893. 443) and by Way mouth Reid (Philos. Transact. Ser. 

 B. 192. 1900. 211). 



He makes the very interesting observation that during the 

 period of digestion the Cl-percentage in the visceral fluid is 

 lower than in sea water. This phenomenon is most pronounced 

 during the actual digestion, after resorption has taken place 

 the difference is only very slight. I could myself verify the latter 

 stratement, but at the same time I observed that it still always exists, 

 in some hasty experiments which I made as soon as Enriques' 

 paper came into my hands. On the same day on which the 

 animals were brought into the laboratory, he eventually found as 

 little as I. 84 gr. "/q of CI. in older specimens kept in captivity 

 for some time, the concentration of the chlorides sometimes was 

 the same as that in sea water, i.e. 2.11 "/q. The same thing holds 

 true for the sulfates which he titrates with barium chloride. 

 He explains this peculiar phenomenon thus: during the period 

 of digestion when the larger molecules are broken up into 

 smaller ones by hydrolysis, the osmotic pressure inside the gut- 

 wall increases. Consequently water diffuses out into the gut, 

 diluting the sea water which was present at first. Consequently 

 the percentage of chlorides in this liquid, decreases. It does not 

 increase in the coelomic liquid, however, as experiments show. 

 The assumption is therefore made, that regulatory processes 

 take place either through the water-lungs or through the many 

 other places where the perivisceral fluid comes in close contact 

 with the surrounding medium, the sea. 



Gradually the products of hydrolysis are resorbed now and 

 the contents of the gut become hypotonic. Practically no chlo- 

 rides can enter into the gut, but the water is resorbed back 

 with the food substances in it. 



The blood system becomes full of liquid, consequently the 

 vessels begin to pulsate — see above — and distribute the 

 food all over the larger part of the body. Part of it is given 



