532 INFECTION AND RESISTANCE 



the antiferment properties were destroyed by lipoid solvents. They 

 did not settle the question satisfactorily because their results were in- 

 consistent, but Jobling and Petersen 25 found that antiproteolytic 

 activity of blood serum was almost wholly inhibited when sera were 

 extracted for several days with chloroform or ether at room tempera- 

 ture or with chloroform in the incubator for an hour. The anti- 

 ferment could be recovered from the ether and chloroform solution, 

 and its action could be destroyed by incubation with iodin or po- 

 tassium iodid. They believed this to be due to the saturation of 

 the free carbon atoms. Furthermore, the same authors showed that 

 toxic substances analogous to anaphylatoxins could be produced in 

 serum when incubated with chloroform. The lipoidal nature of the 

 antiferments is a likely one although it does not account for the fact 

 noticed uniformly by all workers that the antitryptic activity can 

 be entirely eliminated by heating the serum to 70 C. for a half hour. 

 This was the observation which at first gave rise to the idea that the 

 antiferment was in itself an enzyme. For this phenomenon of heat 

 lability no satisfactory explanation has as yet been advanced. 



The recent researches of Abderhalden 2G upon the intravascular 

 digestion of foreign substances introduced into animal bodies prom- 

 ised to have considerable bearing upon problems of immunity. 

 Abderhalden, whose work we cite chiefly from his monograph, "Die 

 Schiitzfermente des tierischen Organismus," took as his point of de- 

 parture the conception that the animal body must necessarily preside 

 over a mechanism whereby it can assimilate foreign substances which 

 obtain entrance unchanged into the circulation. Abderhalden be- 

 lieves that this process depends upon the mobilization of "protec- 

 tive ferments," a term which he borrows from Heilner, 27 and sug- 

 gests the possibility that these ferments may originate in the leuko- 

 cytes. 



Experimentally Abderhalden approaches his problem by deter- 

 mining the presence of specific ferments in the blood of animals into 

 which various foreign substances have been introduced by paths 

 other than the alimentary canal. For this purpose he has developed 

 a number of methods, the most important of which are his optical 

 method and his dialysis method. The optical method used for the 

 determination of the proteolytic properties of the serum depends 

 upon the fact that many of the amino-acids are optically active. 

 Moreover, most of these substances are chemically known and their 

 optical activity determined, so that it is possible to take blood serum 

 which is to be examined for its contents of particular ferments, mix 



25 Jobling and Petersen. Journ. Exp. Ned., 1914, Vol. 19, p. 480. 



26 Abderhalden. "Schiitzfermente des tierischen Organismus," Springer, 

 Berlin, 1912. 



27 Heilner. Cited from Abderhalden Zeitschr. f. Biol., Vol. 50, 1907. 



