394 BOARD OF AGRICULTURE. [Pub. Doc. 



way, subjected to an exhaust pressure of sufficient force to strain 

 the purely fluid parts of the contents out through the porcelain. 

 This filtered fluid does not contain any of the bacilli. The fluid 

 is next proper!}" evaporated, which drives ofl' the surplus water 

 and concentrates the tuberculin. When this concentration 

 reaches a certain point the fluid is carefully bottled, under con- 

 ditions which absolutely prevent the introduction of any germ, 

 in order that it may be kept unchanged. When the fluid is to 

 be used it is properly diluted to a certain standard and again 

 carefully bottled. 



In making the test, a very small quantity of this tuberculin 

 is injected under the skin of the animal, three drops of the 

 concentrated tuberculin, or thirty drops of a ten per cent, solu- 

 tion, from whence it immediately enters the blood. Experience 

 has shown — and this is the value of the test — that if this very 

 small dose is injected into an animal which already has tuber- 

 culosis, it is sufficient to produce a fever in the animal ; that if 

 the animal is free from tuberculosis, — that is, if the living 

 bacilli of tuberculosis are not in its system, — the dose injected 

 is not sufficient in quantity to make any impression whatever, 

 and is promptly eliminated. 



Whether or not the fever has been created in a given animal 

 by the tuberculin is demonstrated by the proper use of the 

 clinical thermometer and a careful study of the tabulated results 

 obtained ; and so accurate are its results, that we have been 

 able to make hundreds of consecutive examinations upon ani- 

 mals, under ordinary farm conditions, without a single error. 



Our method of making the test is invariable : a sufficient num- 

 ber of preliminary examinations are made with the thermometer 

 to ascertain accurately the normal temperature of the given 

 animal, these examinations being made at, as nearly as possible, 

 the same time of day in all cases. The normal temperatures 

 having been ascertained and recorded, the injection of tuber» 

 culin is made in the evening. Eleven hours after the injection 

 w^e commence taking and recording the trial temperatures. 

 These are taken each two hours until the test is finished. The 

 time required to properly complete this part of the test varies 

 considerably ; it may roughly be stated ai: from six to thirty 

 hours, with an average of about twelve hours. It may be of 

 interest to show the behavior of the thermometer in one of these 



