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COLLOIDS IN BIOLOGY AND MEDICINE 



G. MALFITANO and J. DUCLAUX use their sacs chiefly for ultrafil- 

 tration though they are equally useful for dialysis. Biologists fre- 

 quently use little reed sacks for dialyzing; they are frail though 

 sterilizable, but their capacity is small. 



SCHLEICHER and SCHULL (DUREN) sell dialyzing thimbles. They 

 are tubular, closed at the bottom, moderately firm, made of parch- 



FIG. 11. Collodion sacs. (A. Schoef .) 



ment and, since they maintain their form, they are useful for certain 

 experiments. They are employed in the Abderhalden test. 



R. ZSIGMONDY * 3 constructed a very useful "star dialyzer." 1 The 

 hard rubber ring B (see Fig. 13) is covered by a membrane (col- 

 lodion, parchment or the like) and is placed on a plate A, which 

 carries the star-shaped support. Through the central opening in the 



1 Obtainable from ROBERT MITTELBACH, Gottingen. 



