SERUM ENZYMES 533 



them with a suitable protein, or preferably a polypeptid, and de- 

 termine with a polariscope the rotation which takes place. We will 

 not go into the technique of this method more extensively because 

 we have no personal experience with it, and the method is one of 

 such delicacy that it is best obtained from Abderhalden's original 

 publications directly. 28 His dialysis methods depend upon placing 

 the blood serum and fermentable substance into dialyzing bags, sus- 

 pending them into distilled water, and determining the presence of 

 peptone, amino-acids, or total nitrogen in the liquid outside of the 

 bag after definite intervals of time. 



By these and other methods Abderhalden 29 has carried out tests 

 with a large number of different substances. Experimenting first 

 with proteins, he injected egg albumen, horse serum, silk peptone, 

 gelatin, edestin, casein, etc., into dogs and rabbits, then, several days 

 later, bled the animals and mixed 0.5 c. c. of the serum with 0.5 c. c. 

 of a solution of the respective substances which had been injected. 

 He found in such cases that definite proteolytic action was exerted 

 upon the injected substances by the active serum of a treated animal, 

 whereas, in the case of most of the substances used, the normal serum 

 possessed no proteolytic action whatever. These results were con- 

 sistently obtained both by the dialysis and by the optical methods. 

 It should be especially noted that the ferments studied by Abder- 

 halden were not as specific as are the antibodies which we have dis- 

 cussed in another place. For Abderhalden found that the serum of 

 an animal treated with proteins developed enzymes which were active, 

 not only against the particular protein used for injection, but rather 

 against proteins in general. They were specific only in that, when 

 produced with proteins, they were not active against fats or carbo- 

 hydrates. This is especially important in connection with the recent 

 discussion concerning the identity of Abderhalden's protective fer- 

 ments and the specific protein antibodies. 



In later experiments Abderhalden claimed to show further that 

 similar ferments could be induced in animals by treatment with car- 

 bohydrates and with fats. The serum of normal dogs is not capable 

 of splitting cane sugar. However, the blood serum or plasma of a 

 dog that has been treated with cane sugar develops the property of 

 inverting the cane sugar into dextrose and fructose within fifteen 

 minutes after injection. This could easily be determined both by 

 putting together the serum with cane sugar and determining the 

 increase of reducing powers, and by means of subjecting such active 

 plasma or serum, together with saccharose, to polariscopic examina- 

 tion. 



28 See especially Abderhalden, Hoppe-Seyler, Zeitschr. f. pTiysiol. Cliemie, 

 Vols. 60, 65, and 66; also "Handbuch der Biochem. Arbeitsmethoden," Vol. 

 5, p. 575, 1911. 



29 Abderhalden. "Schiitzfermente," p. 49. 



