DEFENSIVE FERMENTS 251 



by means of determining the amino-nitrogen, found that practically every 

 serum shows some degree of protein digestion when incubated with 

 placental tissue. Van Slyke's methods are so accurate that it seems 

 probable that the ninhydrin tests with dialyzates must vary consider- 

 ably, depending upon the amount of dialyzable substance which may 

 pass through any given thimble. Elsesser worked with the purified 

 vegetable proteins of Osborn and found that at best the specificity of 

 the reaction is less than that of anaphylaxis and that there are many 

 non-specific results. Boldyreff found that the ferments act not only 

 upon placental proteins but also upon other varieties of protein; he 

 believes that the method is excellent for detection of proteolytic enzymes 

 in the blood but as a distinctive sign of pregnancy it is useless. Against 

 these views are the recent results of Retinger, who claims that it is 

 not only possible to demonstrate lesions of the brain by this test but 

 further to define within fairly small limits the localization of the 

 lesion. It may be that with further modifications a test of some clini- 

 cal value can be developed upon the basis of the Abderhalden test. At 

 the present time, there is little reason for accepting the conception of 

 specific ferments and the test has been entirely discarded in 

 many laboratories. 



