308 IMMUNOLOGICAL METHODS OF DIAGNOSIS 



which we have just become acquainted, the thought naturally sug- 

 gests itself that any component of the body may in the end be viewed 

 as alien to other parts of the body, if it is placed in surroundings 

 which are in reality alien to that particular component. It is thus 

 quite conceivable that the presence in the circulation of some of 

 the body's own cells might give rise to similar reactions providing 

 that the cells in question are really foreign to the interior of the 

 bloodvessels, i. e., to the blood plasma or the blood cells. As this 

 takes place not only under various pathological conditions, but even 

 during pregnancy, where chorion cells have been shown to enter 

 the circulation, it was natural to put the question to the experimental 

 test. As a result Abderhalden announced that he succeeded in 

 demonstrating that the blood serum of pregnant animals has 

 acquired the power of causing the cleavage of placental peptone 

 and placental proteins. 



While his experiments were originally conducted by bringing 

 together the serum of the pregnant animal and the placental peptone 

 in the tube of the polarimeter, when a gradual change in the degree 

 of rotation could be noted as the cleavage took place, he subsequently 

 discovered that the same reaction can be demonstrated by placing 

 the placental tissue together with the blood serum of the individual 

 in a dialyzing tube and then testing the dialyzate for biuret. To 

 this end the following procedure is recommended. 



Abderhalden's Test. Preparation of the Antigen. A fresh placenta 

 is stripped of its membrane, cut into small pieces and washed free 

 from blood by kneading the material in running water. It is then 

 placed in boiling water which has been slightly acidified with acetic 

 acid (2 drops of the glacial acid to a liter of water), and the boiling 

 continued for five minutes. The supernatant fluid is decanted and 

 replaced by a corresponding quantity of water. The boiling is con- 

 tinued for five minutes longer, and the water then tested for biuret 

 (see below). So long as a positive reaction is obtained the tissue 

 is boiled with new portions of water, until finally it is placed in a 

 bottle (together with the last portion of water) and covered with 

 a layer of toluol. In this form it keeps practically indefinitely. It 

 is advisable nevertheless to assure one's self from time to time that 

 the biuret reaction is still negative; if this should not be the case 

 the material is boiled with new portions of water until the desired 

 end has been attained. 



