328 IMMUNOLOGICAL METHODS OF DIAGNOSIS 



tional specimens of serum with a tissue with which no reaction is 

 expected, besides at least one additional serum-placental specimen, 

 and to duplicate all serum-tissue specimens with inactivated serum. 

 The bottles are then placed in the incubator and left for the requisite 

 number of hours within which the dialyzers in use have been found 

 to work, when the dialyzate (10 c.c.) is tested with ninhydrin as 

 described. If the test is satisfactorily positive only the active serum- 

 placental tissue specimens should show a purplish-violet color. 

 The intensity of the reaction varies considerably, and is no doubt 

 in part dependent upon the tightness of the dialyzer. For the most 

 part a fairly intense color is obtained, but with very tight tubes 

 I have frequently gotten only a faint purple which was scarcely 

 noticeable with daylight, but which showed up quite plainly with 

 artificial (electric) light, when the tube was placed upon a white 

 ground. 



Results. Abderhalden's claim that a positive, specific reaction 

 may be obtained in every case of pregnancy, even as early as the 

 first month, has been substantiated by numerous investigators. 

 But the literature upon the subject also contains numerous adverse 

 criticisms and reports of non-specific reactions under various patho- 

 logical conditions, negative reactions in cases of actual pregnancy, 

 besides positive reactions in normal non-pregnant individuals, so 

 that the uninitiated may well' be in doubt what and whom to believe. 

 Every conscientious and critical worker no doubt has himself passed 

 through three phases in reference to this problem: The first charac- 

 terized by a spirit of overconfidence and ignorance of the pitfalls 

 connected with the method, the second one of utter dejection and 

 pessimism, and the third one renewed optimism based upon hard 

 work and painstaking personal observations. A publication of 

 results based upon the phase in which the worker finds himself at 

 the time would naturally present widely differing views on the part 

 of the same observer, but evidently only those results would really 

 be of value which are published during the third phase of acquired 

 wisdom. I, personally, feel that I have passed through the most 

 strenuous period of my apprenticeship and that I have acquired 

 the right to speak with optimism regarding the present value and 

 the future of the principle underlying the Abderhalden method. 



