PRECIPITIN TESTS IN SYPHILIS 



459 



tioiis. Ill this laboratory, very fine clumps have been considered 

 as doubtful reactions and without diagnostic value. 

 Typical microreactions are shown in Figs. 20-23. 



Fig. 20. Fig-. 21. 



Fig. 22. 



Fig. 20. — Photoinicrogiapii of a .strongly positive Kline test. (Dark-flcld illu- 

 mination. ) 



Fig. 21. — Photomicrograph of a moderately positive Kline test. (Dark-fleld 

 illumination.) 



Fig. 22. — Photomicrograph of a weakly po.sitivo Kline test. (Dark-field illu- 

 mination.) 



Fig. 23. — Photomicrograph of a negative Kline test. (Dark-flcld illumina- 

 tion.) 



The strongly positive reaction (Fig. 20) has large microscopic 

 clumps. As the reagin titer decreases, the clumps become smaller 

 (Figs. 21 and 22). A typical negative reaction (Fig. 23) has 

 a number of needlelike crystals equally distril)uted over the field. 



