DIGESTION AND ABSORPTION 177 



within the dialyzer to stop the increase of the volume of its contents ? 

 (Endosmotic pressure.) Will that amount of pressure prohibit diffu- 

 sion between the liquids? 



(2) After osmosis has been allowed to take its unimpeded course 

 for, say, one hour, starting with a 20 per cent, solution of NaCl within 

 and distilled water without the dialyzer, note the height of the water 

 in the tube and compute the number of grams of water which have 

 entered the dialyzer. Determine how much NaCl has passed out 

 of the dialyzer. An easy and sufficiently accurate method is to evap- 

 orate to dryness all or a known proportion of the liquid in the outer 

 receptacle, and weigh the dry salt remaining. How many grams of 

 water enter the dialyzer for each gram of salt that leaves? (Endos- 

 motic equivalent.) 



(3) Is the endosmotic equivalent constant for salt and water? 

 (a) Is it the same for different strengths of the salt solution i. e., 



for 10 per cent, or 1 per cent, as for 20 per cent. ? (b) Is it the same 

 for two hours or four hours as for one hour? 



(4) Fill with 10 per cent, glucose three dialyzers provided with 

 three different kinds of membrane. Does osmosis take place at the 

 same rate in all three dialyzers? What is the endosmotic equivalent 

 for glucose? 



(5) What is the endosmotic equivalent for dilute egg albumin? 

 When albumin is injected into the colon it is readily absorbed as 

 albumin, there being no digestive changes in it. 



(6) Fill a .dialyzer with equal parts of 10 per cent, glucose and 

 10 per cent. NaCl. At the end of a convenient period, two to six 

 hours, determine whether these substances have diffused according 

 to their own endosmotic equivalents i. e., independent of each 

 other, or have they been influenced, the one by the other? 



