160 LECTURES ON IMMUNITY 



tides of mastic with a thin film, after which the particles 

 behave as if they consisted of drops of gelatin or serum. 



Recently there have been many efforts made to place in 

 parallel the properties of egg-white and its derivatives, as 

 peptons or albumoses, with those of inorganic colloids, 

 which after all consist of suspensions of particles of ultra- 

 microscopic magnitude. These are generally precipitated 

 by the solution of very small quantities of salts in the 

 suspending water, and they assume an electric charge 

 on contact with the water, whereby they wander to the 

 one or to the other pole of a battery submerged in the solu- 

 tion. The solutions of egg-white and its derivatives seemed 

 at first to behave in the same manner. But as Bechhold 

 says, the albumoses, etc.", do not behave otherwise than 

 common solutions. The same is evidently true of different 

 albuminous substances, according to the recent investiga- 

 tions of Pauli. 1 He subjected ox or horse serum to dialysis 

 for a very long time, six to eight weeks. This serum did 

 not migrate with or against the electric current, and it was 

 not precipitated by weak solutions of alkaline salts, nor 

 of salts of zinc, copper, iron, mercury, or lead. It was 

 coagulated by strong heat, alcohol, and strong solutions 

 of alkali salts or zinc sulphate. These sera contain two 

 different kinds of protein, albumin and globulin. These 

 could not be separated by means of the current, so that 

 neither of these substances was carried by the current. 

 The great difference between the so-called organic colloids 

 and the inorganic or true colloids caused Pauli to express 

 the opinion that we should not attempt to deduce the 

 properties of organic from those of the inorganic colloids, 



1 W. Pauli: HofmeisUrs Beitragc, 7. 531 (1906). 



