272 FERMENTS AND ANTIFERMENTS 



inactivation considerably weakens the reaction, but does not abolish it 

 altogether. 



3. Specimens of blood sent through the mails are really unsatisfac- 

 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 sufficient amount of the prepared placenta for the work 

 at hand with sterile forceps and wash in a dish of sterile distilled water 

 to remove toluol and chloroform. Boil with 4 or 5 volumes of sterile 

 distilled water for two minutes and test the water with ninhydrin. 

 If positive, the tissue must be boiled as described above until free of 

 ninhydrin reacting substances. 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 with 

 sterile forceps 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 J4 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- 



