230 CLINICAL DIAGNOSTICS. 



or passive refractoriness to reasonable demands is regarded as 

 balkiness. 



Young animals, such as are not yet sufficiently accus- 

 tomed to work, also evince a certain degree of refractoriness, 

 but, as a rule, if properly handled they will soon yield and 

 obey willingly, especially if they are hitched with older and 

 quiet horses. 



13. Diagnostic Inoculation. 



Diagnostic inoculations consist in the introduction of cer- 

 tain substances into the bodies of animals for the purpose of 

 determining either the character of the substance or the con- 

 dition of the animal's health. We base our judgment on the 

 character of the result. For the clinician diagnostic inocula- 

 tions serve merely to recognize a few infectious diseases ; cer- 

 tain of these diseases have so rapid a course that the clinical 

 symptoms cannot be relied upon to determine either their kind 

 or character with any degree of certainty. Others which ter- 

 minate much less rapidly do not show sufficient symptoms for 

 a definite diagnosis. In these cases nothing save 

 a correctly performed inoculation will 

 serve to recognize the disease or to ob- 

 tain an early diagnosis. 



Diagnostic inoculations are always made with respect to 

 certain well known infectious diseases which our examination 

 leads us to suspect. In performing the inoculation, therefore, 

 we must consider the peculiarities of these diseases, we choose 

 certain tissues, fluids or other substances for our inoculating 

 material, we follow a certain method of inoculation and make 

 use of particular animals. 



For inoculation we use 



1. Material of known composition (tu- 

 berculin, mallein) in order to determine the condi- 

 tion of the animals from the resulting reaction. 



2. Tissue and other material from diseased an- 



