DISEASES OF SWINE 489 



boars being 39 C., and for the sows 39.16 C., the higher tem- 

 peratures of the sows 'being thought to be due to excitement, owing 

 to their racing about when let out of their pen. The temperatures 

 of all of the pigs were higher at the preliminary reading than at 

 subsequent testings, probably the result of being caught and han- 

 dled. 



The tuberculin was injected at 10 p. m., and the temperature 

 of each pig was taken at 7 o'clock the following morning and each 

 two hours afterwards until the veterinarian of the purchasing 

 party was convinced that no trace of tuberculosis existed in any of 

 the animals. The variations in the temperatures of the various 

 pigs were comparatively slight, that of one boar being from 39.2 

 to 38.5 C., and of one sow from 39.4 to 38.5 C., the highast 

 being in each case the one taken first. The average temperature 

 of all the pigs at the various testings was 38.6425 C., or nearly 

 0.3 C. less than those first taken. (B. A. I. Cir. 144.) 



Tuberculin is a product of the growth of the tubercle bacillus. 

 It is prepared by sterilizing, filtering, and concentrating the liquids 

 in which the tubercle bacillus has been allowed to multiply in the 

 laboratory. This substance was first made and studied by Koch, 

 and it was found that when injected into the tissues of a tubercu- 

 lous animal it had the effect of causing a decided rise of tempera- 

 ture, while it had no such effect upon animals free from tubercu- 

 losis. The value of tuberculin for revealing the existence of tuber- 

 culosis was tested by many investigators during the years 1890 

 and 1891. The injection of this new drug was at once recognized 

 as a most remarkable and accurate method for the detection of 

 tuberculosis, even in the early stages and while the animal ap- 

 peared to be in perfect health. Our knowledge of the tuberculin 

 test was built up through the most careful and thorough scientific 

 experimentation and should be accepted as entirely reliable. In 

 practice the tuberculin test is conducted by first taking the tem- 

 perature of the animal to be tested, at intervals of about two hours, 

 a sufficient number of times to establish the normal temperature 

 of the body under the ordinary conditions of life. The proper 

 dose of tuberculin is then injected under the skin with a hypo- 

 dermic syringe. (B. A. I. B. 38.) 



Before entering upon a discussion of the tuberculin tests it 

 is desirable to say a few words about the temperature of hogs gen- 

 erally. The normal variations that occur in individual hogs are 

 very great, so great, indeed, within short periods of time, and 

 from apparently inadequate and frequently undiscoverable causes, 

 that it seems at first that they are wholly incompatible with the 

 successful application of a test which depends, for the information 

 that can be derived from it, on a reasonable constancy of the tem- 

 perature in the absence, and an increase of the temperature in 

 the presence, of a specific disease. In addition to this variation in 

 the individual animal, when the temperature of a number of 

 hogs is compared the difference found is of such magnitude that we 

 are at a loss to conclude what should be regarded as normal. 



