361 



parts of water, gives even more satisfactory preparations 1 than 

 India ink. It is used in the same way. Thin films of the serum - 

 on slides or cover-glasses may be stained as directed above. Micro- 

 scopic examination of fluid obtained by gland puncture or from 

 secondary lesions on the skin or mucous membranes is carried 

 out in the same way. Serious confusion in the recognition of the 

 spirochete is likely to arise in the case of lesions in the mouth or 

 pharynx, inasmuch as some of the normal mouth spirochetes are 

 very similar in form to Sp. pallida. The presence of typical 

 spirochetes in the juice aspirated from a lymph gland is practically 

 diagnostic, and the recognition of typical organisms in genital 

 chancres or lesions on the skin has considerable diagnostic value. 



Inoculation of animals is of little practical use in diagnosis, 

 but it has been possible by this method to demonstrate the fre- 

 quent presence of Sp. pallida in the circulating blood in cases of 

 untreated secondary syphilis. 



The detection of antibodies in the blood of the patient is under- 

 taken in two ways, first by the complement-fixation ( Wassermann) 

 test and second by the luetin test. For the complement-fixation 2 

 test, as performed at the Laboratories of the New York Post- 

 Graduate Medical School and Hospital by Dr. R. M. Taylor, 3 

 the following are employed: 



1. The red blood cells are obtained by defibrinating fresh 

 sheep's blood, filtering it through paper if necessary to remove 

 fragments of clot, separating the cells in the centrifuge and wash- 

 ing them four times with 0.9 per cent salt solution. Finally i c.c. 

 of the corpuscles as packed by the centrifuge is suspended in 

 19 c.c. of 0.9 per cent salt solution; 0.2 c.c. of this suspension is 

 arbitrarily taken as the unit of red blood cells. 



2. The complement is obtained by drawing 5 to 10 c.c. of 

 blood from a large guinea-pig by cardiac puncture. This blood 

 is transferred to a Petri dish, allowed to clot, incubated at 37 C. 



1 Harrison: Journ. Roy. Army Med. Corps, 1912, Vol. XIX, p. 749. 



2 For a detailed discussion see Citron-Garbat, Immunity, Phila., 1912; Simon, 

 Infection and Immunity, Phila., 1912. 



3 1 am indebted to Dr. Taylor for the details of this procedure. 



