PRACTICAL APPLICATIONS 417 



fever. It is rarer in other diseases, but isolated examples have 

 been met with in systematic investigations in a great many 

 maladies ; but here it is the exception, whereas in syphilis it is 

 the rule. In primary and secondary cases it occurs in 90 per 

 cent, or more, and is present in the majority of patients suffering 

 from tertiary syphilis and " metasyphilitic " affections. It is very 

 frequently found in the cerebro-spinal fluid of general paralytics 

 (80 per cent, 90 per cent., or more), even when it is absent from 

 the blood. It is not so common in tabes, and is extremely rare 

 (if it ever occurs) in the cerebro-spinal fluid in non-syphilitic 

 diseases, with the curious exception of scarlet fever, in which it 

 is almost constant. 



So far there is no theoretical difficulty in the interpretation of 

 the phenomenon, but a new fact discovered by Landsteiner, 

 Miiller and Potzl seems to show that the reaction is of a nature 

 entirely different from the ordinary Bordet-Gengou phenomenon. 

 They found that an alcoholic extract of a normal organ (e.g., of a 

 guinea-pig's heart muscle) might be used instead of a tissue rich 

 in spirochsetes ; and further researches have shown that the lipoid 

 substances isolated therefrom, or even comparatively simple 

 substances, as lecithin and taurocholate and glycocholate of soda 

 (Levaditi and Yamanouchi) give the reaction, although apparently 

 not so frequently, as when an extract from a syphilitic organ is used. 

 The "antigen" is soluble in hot alcohol, and this fact alone removes 

 it from the group of true antigens, which, as we have seen, are 

 apparently all proteid in nature. According to Levaditi, the sub- 

 stance occurring in the blood or cerebro-spinal fluid is not an anti- 

 body at all, but either lipoid substances or salts, or the two in 

 combination, and they are set free when tissues are broken down in 

 a certain way, which occurs most frequently in syphilis, but may 

 take place in other diseases. Under ordinary circumstances they 

 are present in a colloid state/but form a precipitate with the lecithin 

 and allied substances extracted from normal organs by hot alcohol, 

 and to this precipitate the complement attaches itself. According 

 to Forges, the serum of syphilitics has the power of precipitating an 

 emulsion of lecithin (0*5 gramme, shaken up with 0*5 per cent, 

 solution of carbolic acid in normal saline) when mixed therewith 

 in equal parts. This he proposed as a test for syphilis, and Nobl 

 and Arzt found it successful in 80 per cent, of cases. Subsequently, 

 Forges replaced the lecithin (which as usually bought is not con- 

 stant in composition) by a recently prepared I per cent, solution 



2? 



