1 88 TECHNIQUE OF THE COMPLEMENT FIXATION METHOD 



4. Immune hemolysin of a rabbit against 



human erythrocytes. 



5. Washed human erythrocytes.' 



From a practical standpoint, however, no distinct advantage is offered by these 

 modifications. In fact, it is the claim of Wassermann and his pupils that by the use 

 of human blood, the error tends toward the opposite direction, i.e., the percentage of 

 positive results obtained are higher than is actually the case. 



The number of modifications have become so numerous that almost 

 every one employs his own "method." There is absolutely no necessity 

 for this, as an innovation justifies its existence only if it is a distinct 

 improvement, i.e., discloses a new fact or radically simplifies the old. 



It is the classical Wassermann reaction performed in the original 

 manner which has taught physicians how valuable a clinical aid it is. 

 Their knowledge has not advanced materially with all the new changes. 

 A single advantage only has been instituted through all this agitation, 

 and that was the discovery that the luetic antigen can be replaced by the 

 alcoholic extract of guinea-pig's heart. In important differential diagnosis, 

 however, even this extract should not be considered as specific as luetic liver 

 antigen. 



For general work, however, its employment may be of service. 



The antigen of Landsteiner, Miiller and Potzl is prepared as follows: 



The heart of a guinea-pig is washed free of blood, its muscular part finely divided or 

 macerated in a mortar and then extracted with 95 per cent, of alcohol for several 

 hours at 60 C. One gram of the heart substance should be mixed with 5 c.cm. of the 

 alcohol. The material is then passed through filter-paper, the nitrate being kept at 

 room temperature. (The editor prepares the alcoholic extract by simply placing the 

 finely divided guinea-pigs' hearts into 95 per cent, alcohol and allowing them to remain 

 there for four weeks for purposes of extraction. At the end of this period the alcoholic 

 solution is titrated and can be employed as antigen.) 



These authors also employ the so-called drop method: 



Drop Ten drops of saline and i drop of normal guinea-pig's serum as comple- 

 Method. ment are placed in each test-tube. The individual tubes receive the 

 following additional ingredients: 



First tube: One drop of the inactivated serum for examination. 



Second tube: Same as one + 2 drops of the alcoholic heart extract. 



Third tube: One drop of inactivated, surely luetic serum. 



Fourth tube: Same as three + 2 drops of alcoholic heart extract. 



Fifth tube: One drop of inactive normal serum. 



Sixth tube: Same as five + 2 drops of alcoholic heart extract. 



Seventh tube: Two drops of extract. 



The tubes are well shaken and placed in the incubator for one hour at 

 37 C. Then i drop of a .50 per cent. (!) suspension of washed sheep's 

 erythrocytes and i drop of hemolysin (double the minimum hemolytic 

 titer) are added. After one-half hour in the incubator, the results are 

 read. 



