THE WASSERMANN REACTION 625 



the limit of each volume with ink with a mapping pen, and 

 subsequently burning in the marks by cautious heating in the 

 Bunsen flame. 1 Calibration should be done soon after the 

 pipettes have been drawn out, so that the glass is dry and per- 

 fectly free from grease and dust. The ends of the pipettes should 

 be cut off perfectly square with a good glass-cutting knife before 

 graduation. After graduation the throttle is inserted and 

 cemented in with sealing wax (for details, see p. 60). Failing a 

 hsemoglobinometer pipette, the mercury may be weighed out 

 (20 cub. mm. = 0-270 grm., but any other weight might be used 

 as the unit volume, e.g. 0-25 or 0-30 grm.). Duplicate pipettes 

 should always be at hand in case of breakage. The pipettes are 

 actuated by a stout rubber teat. With care (and luck) these 

 pipettes will last many months, with occasional re-marking if the 

 graduations become faint. The pipettes should be rinsed with 

 saline before use, and with saline and then with absolute alcohol 

 after use. After draining and removal of the teats they may be 

 kept in a box. Care should be taken not to wet the throttle, or 

 the pipette will not aspirate. If this occur, moisture may be 

 removed by absolute alcohol. 



The collection and preparation of the sera, the saline, sheep's 

 corpuscles, guinea-pig complement and antigen and daily routine, 

 are the same as for the " large volume " technique described in 

 Sections I, II, and IV, pp. 614, 615, 617. Less patient's blood is 

 required, 0-5 c.c. is ample, and about 0'2 c.c. of serum is pipetted 

 off into a quill tube numbered to correspond with the specimen, 

 and the quill tubes of sera are inactivated for 10-15 minutes ; 

 5 c.c. of guinea-pig serum is sufficient for thirty or forty specimens. 

 Of the antigen dilution, 7*5 c.c. suffices for twelve to eighteen 

 specimens, and 15 c.c. for thirty-five to fifty specimens. The 

 sheep's corpuscles should finally be made up into a 25 per cent, 

 suspension. 



A. STANDARDISATION OF THE HJEMOLYTIC AMBOCEPTOR. Refer 

 to Sect. Ill, p. 616, and prepare a 1 in 1,000 dilution of amboceptor, 

 diluted (1 in 2) guinea-pig serum and 5 per cent, suspension of 

 sheep's corpuscles as there described. Take nine quill tubes and 



1 Stephens's blue-black ink is the best. It is a good plan to concentrate 

 5 c.c. to half its volume over sulphuric acid and then to add a little gum, 

 preserve well stoppered, and keep this for marking pipettes. 



M.B. 40 



