ABDERHALDEN'S SERODIAGNOSIS OF PREGNANCY 259 



tory, for even if they are delivered within twelve hours after bleeding, 

 the amount of handling has usually resulted in the breaking up of a 

 number of corpuscles and the tinging of the serum with hemoglobin. 

 The Test. 1. Absolute cleanliness should be employed. The glass- 

 ware should be sterile and dry, and everything should be in readiness. 

 The technic should be aseptic and thoroughly understood. 



2. Remove a portion of the prepared placenta with sterile forceps 

 and wash in a dish of sterile distilled water to remove toluol and chloro- 

 form. Place on sterile filter-paper, and squeeze to remove any excess 

 of water. Weigh and place 0.5 gram in each of two shells (one for a 

 control). 



3. Holding each shell with a second pair of boiled forceps, pipet 1.5 

 c.c. of the patient's serum into one shell containing placenta, and the 

 same amount into a third shell which is to serve as a control on the 

 serum. Place 1.5 c.c. of sterile distilled water in the placental tissue 

 control shell. 



4. Unless one is absolutely sure that neither the tissue nor the serum 

 has touched the outside of the shells, they should be held shut and washed 

 with sterile distilled water. 



5. Each of the three shells is now placed in cylinders containing 

 20 c.c. of sterile distilled water. Under no circumstances are the shells 

 to be loaded while they are in the dialyzing cylinders. 



6. The contents of each shell and the water surrounding them are 

 covered with a layer of toluol about % inch in depth, and the cylinders 

 plugged with cotton to prevent evaporation and contamination. The 

 shell should be at least ^to^ inch above the level of the outside fluids, 

 and due care must be exercised in carrying the cylinder back and forth 

 from the incubator that the contents of the shell and the surrounding 

 water do not become mixed. 



7. If it is at all possible, it is well to set up two more shells as controls, 

 each containing placenta and normal serum and the serum of pregnancy 

 respectively. 



8. All the cylinders are incubated at 37 C. for twenty-four hours. 

 Ten c.c. of the dialysate are then removed from each tube with a sepa- 

 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. 



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 



