148 THE DIALYSATION PROCESS 



contains none of the active ferments capable of de- 

 composing albumen. Should we detect the presence of 

 peptones, we may be certain that some decomposition 

 of the albumen has taken place. In our special 

 case the fluid to be tested is blood serum. It is 

 obvious that the method is exactly the same, when 

 we test, for their capacity of decomposing albumen, 

 such substances as cerebro -spinal fluid, lymph, or 

 extracts from various organs e.g., juices obtained 

 by means of high pressure. 



Dialysing Tubes.- -The result of tests for albumen- 

 decomposing ferments by the dialysation process 

 depends in the first place upon the quality of the mem- 

 brane used. The latter must above all answer two 

 requirements. First of all it must be absolutely im- 

 permeable to albumen, and further, evenly permeable 

 to decomposites of albumen. If the tube allows 

 albumen to pass through it, the latter may be mis- 

 taken for peptones, unless we apply special tests for 

 albumen. Should dialysing tubes be used which 

 allow peptones to diffuse through at a variable rate, 

 then we should be at a loss in our judgment upon 

 the results of a test, because, as will presently be 

 shown, a control test of the fluid to be tested must 

 always be made, without the presence of albumen, and 

 the results of this test be compared with those of the 



tests in which albumen has been mixed in the dialv- 



j 



sing tube with the fluid under research. Should one 



