ABSORPTION 319 



respectively (instead of 75 and 109 c.c.) in experiments 3 and 4. 

 The process becomes clear immediately if we regard absorption as 

 actually a swelling phenomenon. We know from page 67 that ac- 

 cording to F. HOFMEISTER, a swollen gelatin absorbs more salt than 

 water from a dilute salt solution, and that hi the presence of NaCl 

 the absorption of water is stronger than in the case of pure water. 



Further light is thrown on this discovery by the researches of M. 

 OKER-BLOM,* who showed that serum takes up a hypertonic common 

 salt solution more readily than an isotonic one. 



From the table on page 318 we see that a concentrated salt solution 

 which causes shrinking is but slowly absorbed. 



If we consider the absorption of other salts, we find that those 

 which as a rule promote the swelling of fibrin, gelatin, etc., also as 

 a rule promote the absorption of water in the. intestines. Therefore, 

 there is a further parallelism between rapidity of diffusion and fur- 

 therance of swelling. 



From the researches of R. HOBER * l as well as those of G. B. WAL- 

 LACE and A. R. CUSHNY,* we obtain the following series: 



Rate of diffusion: 1 HPO 4 , SO 4 < Fl < NO 3 < I < Br < Cl, 

 Rate of absorption: Fl < HPO 4 , SO 4 < NO 3 < K Br < Cl, 

 Rate of diffusion : Mg < Ca < Ba < Na < K, 

 Rate of absorption : Ba < Mg, Ca < Na, K. 



From this series we see that there is in general a parallelism between 

 the rates of diffusion and of absorption. 



Fl and Ba being powerful protoplasmic poisons, it does not sur- 

 prise us that they form an exception and inhibit absorption. 



Similar relationships between the rates of diffusion and of absorp- 

 tion were determined for a series of organic salts and nonelectrolytes. 



It may be said, then, that slowly diffusing substances are slowly 

 absorbed, and that electrolytes causing shrinking may impede not 

 only their own absorption but also that of others, and that substances 

 rapidly diffusible and favoring swelling act contrariwise. This follows 

 from the investigations of F. HOFMEISTER and his pupils as well as 

 those of H. BECHHOLD and J. ZIEGLER. 



The importance of swelling is especially evident when two different 

 substances are absorbed simultaneously. Let us take for example 

 an experiment of KATZENELLENBOGEN.* Simultaneously with so- 

 dium chlorid, there were introduced glycocol and acetone, which 

 surely do not favor swelling, but the latter rather the reverse, and 

 urea which induces swelling to a high degree. 



1 For I, Br and Cl there have been substituted the diffusion path in jellies 

 instead of rapidit; of diffusion. 



