i/|2 Immunity 



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 — i 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 remove 

 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 be- 

 come perfectly white in color. It now receives loo times its weight of distilled 

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

 looo CO., 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 a jar 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: 



A fragment of the placental tissue is removed from the container with sterile 

 forceps and blotted with sterile filter or blotting paper to absorb the toluol and 

 chloroform. It is then placed upon a sterile filter paper and weighed; about 

 0.5 gram should be placed in each of two thimbles, i.s cc. of the serum to be 

 tested is cautiously pipetted into one thimble; 1.5 cc. of sterile distilled water 

 into the other. Each is then transferred with forceps to a large tube containing 

 20 cc. of sterile distilled water, and the surface of each fluid is covered with 

 toluoL The tubes are now stood in the thermostat at 37°C. for twenty-four 

 hours, at the end of which time a sample of the fluid in each outer tube is tested 

 by boiling for one minute with ninhydrin (0.2 cc. of a i per cent, solution, to 10 cc. 

 of the fluid). The reaction is not read for thirty minutes after boiling. If the 

 conditions are all favorable, i.e., the serum used be from a pregnant woman, the 

 tissue used as substratum beplacenta,theenzymeintheserumactsuponthesub- 

 stratum and transforms its albumins to peptones and amino-acids; if the trans- 

 fusion is perfect in both thimbles, and neither thimbleleaks (this has, of course, 

 been previously tested and security can be counted upon now) the fluid surround- 

 ing the thimble containing the serum should give a bright blue color or positive 

 reaction, and that surrounding the thimble containing the water no color or a 

 negative reaction. 



By the test we are then able to determine, the substratum being 

 known, whether the serum contains an enzyme capable of acting 

 upon or transforming it; or the enzymic character of the serum being 

 known, it may be possible to tell something about the substratum. 



