GENUS BACTERIUM 255 



it seems to be sufficient to prevent the introduction of organ- 

 isms when the needle is inserted. 



4. The dose of tuberculin that is ordinarily given to an 

 adult animal of medium size is 0.25 cc. of the Koch tuberculin. 

 The tuberculin from the laboratories in this country is usually 

 sent out already diluted. Two cubic centimeters is the usual 

 dose of the dilution. 



5. Beginning six or eight hours after the injection, the 

 temperature of the animals should be taken hourly or at least 

 every two hours for eighteen hours after the injection, that is, 

 five or six temperatures at intervals not longer than two hours. 

 If at the end of this time the temperature of any animal ap- 

 pears to be rising it should be taken again and repeated at like 

 intervals until it returns to the normal. 



6. During the time that the test is being made the cattle 

 should be kept quiet, free from all exposure or excitement, and 

 fed and watered as usual. The water should not be too cold. 



7. Reaction. The usual reaction consists in a rise of 

 temperature, beginning about the sixth or eighth hour after 

 injection and continuing for several hours. The rise varies 

 from 1.5 to 4 or 5 above the normal. A reaction, however, 

 does not mean simply a rise of temperature for a brief time, 

 but a gradual rise, a continued high temperature for a few 

 (2 to 6) hours, and then a gradual decline. This is called the 

 tuberculin curve, and it is more important in the interpreta- 

 tion than the simple rise of temperature. In cattle there is not 

 infrequently a normal variation from 1 to 2 in the animal's 

 temperature within twenty-four hours. Cold water, when 

 drunk in considerable quantities, lowers the temperature from 

 2 to 3. A temporary excitement may cause an elevation of 

 from 1 to 1.5. There are often marked variations in the tem- 

 perature of the same animal on consecutive days. 



In many animals there is an organic or constitutional 

 reaction which consists in roughening of the coat, evidence of 

 chill, dullness of the eye, indifference to food, and a general 

 depressed appearance. In milch cows, in case of reaction 

 there is a slight shrinking of the milk, due probably to the rise 



