26 METHODS OF EXAMINATION 



method. The instrument consists of an inverted truncated glass 

 cone in an air chamber which is pierced at one side by a fine metal 

 tube adjusted to throw a fine stream of air at a tangent to the 

 edge of the hanging drop of blood. The drop of blood is placed 

 on the end of the truncated cone. Before coagulation has taken 

 place a very light draft of air sets the corpuscles in the drop of 

 blood in motion. When coagulation has occurred motion is not 

 produced. The process is watched under a low power of the 

 microscope. 



Comparison of the time of coagulation may be made only in 

 cases where the same method and technic have been used. A 

 description of the several methods of obtaining the time of coagula- 

 tion with a discussion of each will be found in Hinman and Sladen's 

 paper. 



TEST FOR SPECIFIC AGGLUTININS OR PRECIPITINS 



The presence of specific agglutinating or precipitating sub- 

 stances is important for the diagnosis of certain infectious dis- 

 eases, as glanders. The blood should be drawn under aseptic 

 precautions. It is convenient to obtain the blood (10-20 cc. is suf- 

 ficient) from the jugular vein by means of a sterile syringe. The 

 bottle and cork in which the blood is placed should be thoroughly 

 sterilized. The technic of making the test is essentially bacterio- 

 logical and will be found in special papers on the subject (see Moore, 

 Taylor and Giltner). 



BACTERIOLOGICAL EXAMINATION OF THE BLOOD 



The blood is obtained under strictly aseptic precautions. Five 

 to twenty cubic centimeters are usually desired. The blood may 

 be obtained from the jugular vein or other blood vessel. A hypo- 

 dermic syringe will be found the most convenient instrument for 

 obtaining the blood. The bottle and cork in which the blood is 

 placed must be carefully sterilized, preferably by long boiling. 

 If sterilized by chemicals the chemicals must be completely re- 

 moved by rinsing several times with sterile water. The methods 

 of examining blood for bacteria will be found in works on bac- 

 teriology. 



