228 MEDICAL BACTERIOLOGY 



in performing the complement fixation tests. Sheep's red blood cells and human 

 red blood cells are those most commonly used. So far as the value and end 

 results of complement fixation tests are concerned it makes no difference whether 

 human or sheep cells are used, statements to the contrary notwithstanding. If 

 one is situated where sheep's cells can be procured they should be used, under 

 other circumstances human cells should be used. If one has access to a sheep 

 slaughter house it is most convenient and economical to obtain the blood there. 

 Sheep kept in the laboratory for this purpose may be bled every week or 10 days 

 without injury. This is done by thrusting a strong, heavy, sharp, hollow needle 

 into the jugular vein after the neck has been shaved. After the needle is with- 

 drawn no dressing .other than styptic collodion need be applied to the wound. 

 When blood is withdrawn from a man for the purpose of obtaining cells, the 

 most prominent superficial vein is sought for, usually at the elbow, the skin over- 

 lying it is washed with alcohol, tincture of iodine applied for i minute and the 

 area again washed with alcohol, a sterile hollow needle is then thrust into the 

 vein and the blood allowed to flow from the needle. 



All the red blood cells required at any one time will be contained in 50 cc. of 

 blood. The blood is collected as follows: A clean sterile glass bottle (200 cc. 

 capacity) having a wide mouth and a ground-glass stopper is half filled with 

 sodium citrate solution(Fig. 3yA); blood is allowed to flow into the bottle until 

 k is three-fourths full (Fig. 37C) it must never be allowed to overflow the 

 stopper is inserted and the bottle shaken to thoroughly mix its contents; it is 

 at once transported to the laboratory and kept in a refrigerator until used. The 

 length of time blood so collected remains fit for use varies from i day to several 

 weeks, hence it is always advisable to obtain it fresh each time it is required. 



To separate the red blood cells the citrated blood is poured into 15-0:. ca- 

 pacity tubes (Fig. 38A) and centrifugalized until all the cells settle; when this has 

 taken place the lower portion of the tubes will show a solid red opaque mass 

 (the cells) above which will be clear, colorless, transparent fluid (serum and 

 citrate solution) (Fig. 386). The supernatant fluid is withdrawn with a pipette, 

 care being taken not to disturb the cells .(Fig. 38C, D). The remaining cells 

 still have some serum and citrate solution surrounding them, this must be re- 

 moved; it is done by washing. The cells are washed as follows: The tubes con- 

 taining the cells are filled to within i or 2 centimeters of the top with normal 

 salt solution, a clean thumb is placed across the top of the tube to confine its 



EXPLANATORY REMARKS TO FIG. 36. 



Ai, A2 and A3. These tubes are for one patient's serum under examination. 



Bi, 82 and 83. These tubes are for a second patient's serum under examination. 



Di, D2 and 03. These tubes contain the known syphilitic patient's serum and are, therefore, control 

 tubes. 



Ei, 2 and 3. These tubes contain non-syphilitic patient's serum and are, therefore, control tubes. 



A i, Bi, Di and Ei contain no syphilitic antigen, therefore these tubes should show an illustrated com- 

 plete hemolysis. 



Ea and 3 show complete hemolysis, indicative of a negative reaction. 



D2 shows no hemolysis. 



D3 only partial hemolysis indicative of a weak positive reaction. 



B2 and 63 show no hemolysis. A strong positive reaction indicative of syphilis. 



A2 and A3 show complete hemolysis, a negative reaction not indicative of syphilis. 



Ji is a complement control tube. Contains nothing but guinea-pig serum and red cells. This tube 

 should show no hemolysis as indicated. 



J2. Hemolytic system control, complete hemolysis. 



J3. Syphilitic antigen control. Complete hemolysis (see pages 243 and 247). 



