58 



Prof. A. E. Wright. On the Measurement of [Aug. 5, 



II. Procedures in connection with the actual carrying out of the 

 Bactericidal Estimation . 



In connection with the actual carrying out of the bactericidal 

 estimation, we have to consider : — 



(1.) The collection of the sample of blood for examination. 



(2.) The preparation of a graduated series of dilutions of the 

 bacterial culture. 



(3.) The special form of capillary-testing pipette required for the 

 subsequent procedures. 



(4.) The method of employing the testing pipette just mentioned, 

 i.e., the method of mixing a series of measured volumes of serum with 

 in each case an equal volume of the successive bacterial dilutions, and 

 the method of determining the sterility or otherwise of the mixtures 

 after the serum has acted upon the bacteria for an appropriate 

 period. 



(1.) Collection of the Sample of Blood. 



The quantity of blood required for an ordinary bactericidal estima- 

 tion need never exceed 1 c.c* Much more than the quantity 

 required can, in the case of man, readily be obtained by driving the 

 blood into the pulp of the finger by winding a handkerchief round the 

 digit, making a prick with a needle or spicule of glass, and then 

 making pressure on the pulp. 



A convenient form of blood capsule is that figured below (fig. 2). 

 The upper end of capsule, when drawn out in a peep flame or in the 

 flame of a lucifer match, provides an aseptic pricker. When proceed- 

 ing to collect the blood both this (A) and the end of the curved limb 

 (B) are broken off. The blood then flows into the capsule, as shown 

 in fig. 3, under the combined action of gravity and capillarity. When 



Fig. 2. Fig. 3. 



* Where only minimal amounts of blood are available, the difficulty can he got 

 over either by the employing very fine capillary tubes or by mixing progressive 

 dilutions of the serum with one and the same dilution of the bacterial culture. 



