"Defensive Ferments 145 



The good shells or thimbles are next to be tested for permeability to peptones. 

 Before this they should be carefully washed in running water and boiled for 

 thirty seconds. 



A I per cent, solution of H6chst "silk peptone" is made in distilled water, and 

 of it 2.5 cc. is pipetted into each thimble to be tested, taking care, as before, that 

 none of the solution by accident drops on the outside of the shell. The shell is 

 now placed in the 20 cc. of sterile distilled water in the wide tube such as was 

 used before, covered with toluol and stood ia the incubator at 37°C. After 

 twenty-four hours, a pipette is thrust through the toluol and 10 cc. of the water 

 taken up. The finger being held over the top of the pipette, the tube is wiped 

 outside with care, so as to get off any toluol, and the fluid then delivered into a 

 test-tube. Here it receives 0.2 cc. of a i per cent, solution of ninhydrin, and- is 

 boiled for exactly one minute. If the peptone has dialyzed, a deep blue color 

 develops after standing for a short time. Good thimbles should be equally per- 

 meable to peptone. The thimble that permits no transfusion of peptone is 

 worthless and should be thrown away. 



The good thimbles are now again thoroughly washed in running water for a 

 minute, or so, and are then transferred to a vessel of sterile distilled water con- 

 taining chloroform to saturation and covered with toluol. 



In making the Abderhalden test it is imperative that the glass- 

 ware used should be chemically clean, that the reagents be pure, 

 that the preparations be kept sterile and that the thimbles and sub- 

 strata should be handled with forceps, not with the fingers. 



To make the test for pregnancy known as the "Abderhalden reac- 

 tion," the foundation of all the other tests of the protective or defen- 

 sive ferments, it is necessary to prepare a substratum upon which 

 the enzyme in the blood may act. 



To do this one obtains a healthy placenta, removes the blood clots, cord and 

 membranes, and washes it in running water. When it is clean on the outside, 

 it is cut into small pieces — r cm. cubes — which are placed upon a towel or on a 

 wire sieve and washed in running water. The purpose of the washing is to re- 

 move every trace of blood serum and of blood pigment. From time to time the 

 bits of tissue are moved about and squeezed by the fingers, and occasionally they 

 are crushed together in a towel. The process is completed when the tissue has 

 become perfectly white in color. It now receives 100 times its weight of distilled 

 water (i gram-i cc), to which are added five drops of glacial acetic acid per 

 1000 cc, and is boiled for ten minutes. The fluid is then thrown away, the tissue 

 fragments are caught in a sieve or cloth, more distilled water added, this time 

 without the acetic acid, and it is boiled again. This is repeated for six times. 

 After the sixth boiling, some of the water is transferred to a tube and tested for 

 proteins with ninhydrin. If the faintest blue color develops upon boiling, the 

 process of washing the tissue by boiling it with clean water, must be repeated 

 again and again until the ninhydrin produces no discoloration after boiling for a 

 minute, and standing for one-half hour. The tissue is then caught on a cloth, 

 finally looked over for any objectionable components, and transferred to ajar of 

 sterile distilled water saturated with chloroform and covered with toluol. 



The blood of the patient is obtained with a Keidel tube or with 

 a sterile syringe from which latter it is at once transferred to a sterile 

 test-tube. When the blood has firmly coagulated, the expressed 

 serum is removed by a sterile pipette to a sterile centrifuge tube and 

 any cells it may still contain are thrown out by centrifugation. 



The technic of the test is more simple than the preparation and 

 preliminary tests it entailed. The glassware being chemically clean 

 and sterile, the thimbles all tested and sterile, and the substratum 

 (placental tissue) ready, one proceeds as follows: 



