386 PATHOGENIC BACTERIA. 



column to which the blood rises can be taken as a proof 

 of actual variation. It may be true that no two of the 

 tubes have exactly absolutely the same contents, but 

 when the given precautions are taken the variation will 

 be so small as to make no significant error in the results 

 obtained. 



The use of the tubes is extremely simple. The ordi- 

 nary puncture is made in the lobule of the ear or the fin- 

 ger-tip of the patient, and one end of one of the tubes 

 touched to the surface of the oozing drop and held there 

 until the blood ceases' to rise in the tube. So little blood 

 is required that a number of tubes may be filled with the 

 blood from a single puncture if desired. The blood in 

 the tube coagulates in a few minutes, and can be allowed 

 to dry, or be drawn to the central portion of the tube and 

 sealed in by fusing the ends in a flame if it be desired to 

 keep it moist. 



When the agglutination reaction is to be made the 

 blood should not be blown out of the tube, as the total 

 quantity contained is small and a large relative quantity 

 will remain in the tube. A better method is to crush the 

 tube in a small crucible or other diminutive vessel and 

 dissolve its contents directly in the culture. 



The proper proportionate amount of culture is meas- 

 ured with a finely graduated pipette (graduated to thous- 

 andths of a cubic centimeter), the calculation according 

 to the standard tube of the writer's experiments being: 

 dilution i : 10 = 0.153 c.cm. of the culture; dilution 

 i : 100= 1.53 c.cm. of the culture; dilution i : 1000 = 

 15.3 c.cm. of the culture. 



The now recognized specific reaction is supposed to 

 take place in dilutions of i : 50, which would require 

 0.71 + c.cm. of the bouillon or diluted agar culture. 



The culture is measured into the little crucible, the 

 blood-containing portion of the capillary tube broken off, 

 dropped in, and subsequently crushed to minute frag- 

 ments and stirred about with a clean, rounded, glass rod, 

 and a drop of the mixture placed as a "hanging drop'* 



