ABDERHALDEN'S SERODIAGNOSIS OF PREGNANCY 273 



rate sterile pipet and placed in sterile test-tubes of the same size and 

 boiled with 0.2 c.c. of the 1 per cent, ninhydrin solution for exactly one 

 minute. After standing for half an hour, the readings are made. 



Bronfenbrenner's Modification. Bronfenbrenner 1 has resolved the 

 technic of the test into two distinct phases : The first comprises a sensi- 

 tization of the substrat by the specific elements of the immune serum 

 at a low temperature, with the resultant absorption of antiferment; 

 the second is the autodigestion of the serum at 37 C. In conducting 

 the test 0.5 gram of prepared placenta is mixed in a sterile tube with 1.5 

 c.c. serum and held in the cold for sixteen hours. The clear serum is then 

 secured by thorough centrifuging and placed in a dialyzing thimble in 

 distilled water as described above, incubated for eighteen to twenty-four 

 hours, and the dialysate tested with ninhydrin. As a further test the 

 substrat may be washed twice with sterile distilled water by centrifuging 

 to remove all traces of serum and placed in a dialyzing thimble with 

 1.5 c.c. fresh male guinea-pig serum. The test is then conducted in the 

 same manner as the regular Abderhalden technic and the usual controls 

 are included. It would appear that this modification has increased 

 the specificity of the test. 



Reading the Reaction. The dialysate of the serum alone should be 

 clear as water or show but the faintest blue tinge. The dialysate of the 

 placenta alone should be clear; the dialysate of the patient's serum 

 plus that of the placenta may show a deep violet-blue color when the 

 reaction is strongly positive, or a fainter blue when it is weakly positive. 

 If this dialysate is water clear or has a faint blue color, comparable to 

 the controls, the result is negative. If there is any doubt, the test 

 should be repeated. The negative control should be water clear or have 

 a faint tinge comparable to its control. The positive control should 

 show a deep violet-blue color. 



I generally control the result given by the shell containing tissue and 

 patient's serum by cleansing it thoroughly, boiling for a minute, and 

 testing it with egg-albumen solution or a serum, in case the reaction 

 was positive, to make sure that the shell has not allowed the passage of 

 serum, or with peptone solution, in case the reaction was negative, to 

 make sure that it was not thick enough to block the passage of peptones 

 and amino-acids. This procedure delays the report on a serum for an- 

 other twenty-four hours, but the greater accuracy obtained warrants the 

 delay. 



Readings should never be made by artificial light. Tubes should be 



1 Jour. Lab. and Clin. Med., 1915, 1, 79. 

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