432 SCIENCE PROGRESS 



and that this property is increased by heat. He concludes 

 therefore that the antipeptic action of normal serum is not 

 specific but is due to a mutual reaction between the colloids 

 of that fluid and the enzyme. Rubenstein (191 6) confirms 

 these results and points out that the serum after being heated 

 neutralises the hydrochloric acid necessary for the pepsin. 



The term " anti-enzyme " has, however, become established, 

 and many writers still use it as if anti-enzyme was a definite 

 entity. From what has been said above there is evidence that 

 such an entity does not exist. 



It is probably more correct, therefore, to refer to the anti- 

 enzyme factor of the blood or tissues, using the term to include 

 any processes or substances which inhibit or retard the action 

 of enzymes. Under this heading would come a substance 

 such as catalase, or mere physico-chemical properties. 



The existence of anti-enzyme factors has been shown by 

 several investigators, but the specificity of the factor is very 

 doubtful. 



Hedin (1912) found that if rennet or its zymogen is injected, 

 an anti-rennet factor is produced ; but he points out that the 

 anti-rennet factor is not a true antibody in Ehrlich's sense of 

 the term. 



Yamakama (191 8) describes an anti-enzyme in the serum 

 which is destroyed by chemical reagents such as chloroform, or 

 saturated monovalent ketones. Yamakama goes on to show 

 that the autolysis of normal serum when alcohol is added is 

 probably due to a similar destructive effect on the anti-enzymes. 



Mention has been made already of the work of Bronfen- 

 brenner, who, when criticising the " Abderhalden reaction," 

 came to the conclusion that during pregnancy certain anti- 

 enzymes were inhibited rather than that new enzymes were 

 formed. 



Other authors similarly neglect the nature of the anti-enzyme 

 factor, but deal with its application. Weil (1916) concludes 

 from his work that the anti-tryptic reaction of the blood may 

 not be specific for any special diseases, but is a valuable adjunct 

 in differential diagnosis, since it is found in some diseases and 

 not in others. 



Much of the work done on anti-enzymes bears a strong 

 resemblance to that of Burge referred to under " Catalase," 

 and if the results of the latter investigator are confirmed a 

 solution will be found as to the nature of many of the " so-called 

 anti-enzymes." 



Perhaps the various anti-enzyme factors which have been 

 suggested as the protective mechanism of the intestinal tract 

 give as good an idea as any of the processes or substances which 

 may be at work, although actually the statement of Hunter 



