380 Diagnostic Value of the Landau Test [April-July. 



The latter Observation is confirmed also by the recent report of 

 Kissmeyer,^ who found the Landau reaction positive in 51 percent 

 of his nonnal control cases. 



Although the findings reported above speak against specificity 

 for the Landau reaction (at least in its present form), it is very 

 interesting to recall that not all sera have equal power to fix iodin. 

 Moreover, although fixation occurs also with sera of nonsyphilitics 

 (30 percent), the frequency of fixation of iodin among syphilitics 

 is much greater (65 percent). The problem is a very interesting 

 one. 



On the basis of our experience we wish to call attention to at 

 least two very important factors in this connection which make a 

 study of this problem very difiicult : One is the importance of estab- 

 lishing the duration-time of the test, in order to avoid a too low (in 

 case of Short duration) or a too high (in case of long duration) 

 percentage of positive reactions. Another important difficulty is 

 the lack of an objective Standard with which to compare the results, 

 since the results of the Wassermann reaction are far from being 

 uniform in the hands of various workers. 



The nature of this interesting phenomenon observed by Landau 

 is an object of further study in our laboratory. 



*Kissmeyer: Hospitalstid, 1914; cited from Deutsche med. Woch., 1914, p. 

 927. 



