CHAPTER IV. 



METHODS OF EXAMINING THE PROPERTIES OF 

 SERUM — PREPARATION OF VACCINES- 

 GENERAL BACTERIOLOGICAL DIAGNOSIS— IN- 

 OCULATION OF ANIMALS. 



The Testing of Agglutinative and Sedimenting 

 Properties of Serum. 



In studying the properties of serum it is necessary to have the 

 means of measuring and diluting small quantities of fluid. The 

 simplest method is by means of 1 c.c. and "1 c.c. pipettes, which 

 can be got from an instrument-maker. Each pipette should be 

 graduated in tenths, and should deliver to the end. If the 

 original amount of fluid to be used is small, say less than '02 c.c, 

 it should be diluted till it has fully this volume. This may be 

 done by drawing up the fluid in a capillary tube (a piece of 

 quill glass-tubing drawn out in the flame being convenient for 

 the purpose) and marking the upper limit of the fluid, the latter 

 then being blown out in a watch-glass. Equal amounts of 

 ■8 per cent, salt solution can be measured out with the marked 

 tube and added till the fluid has the necessary volume. Thorough 

 mixture is effected by drawing up the diluted serum in the quill 

 tubing and blowing out again, this being repeated several times. 

 Further dilutions can be made by the graduated pipettes. 

 Where such pipettes are not available, Wright's method may be 

 used. 



Wright's Method of measuring Small Amounts of Fluids. — A Gower's 

 5 c.mm. hfemoeytometei. pipette and some pieces of quill glass-tubing are 

 required. 



A piece of quill tubing is drawn out to capillary dimensions, and the 

 extreme tip of it is heated in a peep flame and then drawn out till it is of 

 the thickness of a hair, though still possessing a bore. If the point be 

 broken off this hair, and mercury be run into the tube, the metal will be 

 caught where the tube narrows and will pass no further — in fact, though 

 air will pass, mercury will not. Into the wide end of this tube 5 c.mm. 

 of mercury, measured from a Gower's pipette, is run down .till it will go 



