COMPLEMENT DEVIATION 145 



are not easily contaminated and appear to retain their agglutinable qualities for 

 several months. The macroscopic methods are preferable with such dead cultures. 



A very convenient method in general use in Germany is the follow- 

 ing: Make dilutions of serum in ordinary test-tubes (3/4X6 in.) as 

 described for the samll test-tubes. Then take a loopful (2 mg.) of 

 culture from an eighteen to twenty-four-hour-old agar culture and 

 emulsify it thoroughly in the dilution in the first test-tube repeat the 

 process in the second tube and so on. This procedure is much safer 

 than when live cultures are added with a pipette. Again, the dilution 

 is unchanged by this addition whereas it is doubled when an equal 

 volume of culture is added to the diluted serum. A control should 

 always be made in normal salt solution. After incubating, observe 

 flocculent precipitates (agglutination) by tilting the fluid in the tubes 

 to form a thin layer and to obtain the most advantageous light and look 

 for a fine curdy precipitate (aggutination) or a uniformly turbid emul- 

 sion (negative reaction). 



The method of using a slide with two vaselined rings, one containing 

 an emulsion in the specific serum and the other in salt solution is of 

 great practical value. This method is described under cholera. 



Pfaundler under the designation of a thread reaction showed that organisms tended 

 to grow in thread forms in a culture medium containing the homologous serum. 

 Mandelbaum has suggested this as a means of diagnosing typhoid. Take ordinary 

 bouillon containing 1% of sodium citrate. Inoculate it with a culture of typhoid. 

 Now with a bulb capillary pipette take up one part (as marked by a wax pencil) of 

 the patient's blood and fifteen times as much of the citrated bouillon just inoculated 

 with typhoid. Mix the blood and citrated bouillon on a sterile slide or in a test-tube 

 and after drawing up into the lower part of the expansion of the capillary pipette, 

 seal off the capillary end. Now place the sealed-off pipette upright in an incubator 

 and after four or five hours take out from the expanded end a loopful of the clear 

 supernatant fluid (the blood cells settle to the bottom) and if the typhoid bacilli 

 are in chains instead of being single and motile it shows a positive reaction. 



DEVIATION OF THE COMPLEMENT. 



It has been found that if there is not sufficient immune body in a 

 mixture of normal serum, containing abundant complement, and bac- 

 terial emulsion, only a portion of the bacteria will be destroyed. In- 

 creasing the amount of immune body with a constant quantity of normal 

 serum, we reach a point where all the bacteria are destroyed. Now, 

 if we continue to increase beyond this point the addition of immune 



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