No. 7. DEPARTMENT OF AGRICULTURE. 167 



per cent, reacted. Calves under eight months of age were excluded 

 from the test, owing to the fact that the preliminary temperatures 

 ■were too high to make the test of any value. 



The reacting animals were removed immediately' from the herd. 

 A number of these animals were registered, some of which had 

 taken prizes at the Buffalo Exposition in the Guernsey Class. Nearly 

 all of these reactors were in various periods of gestation and it was 

 considered advisable to keep them for their offspring. They were 

 placed in a stable approximately 100 yards from the stables in which 

 the main herd is kept, and situated at the foot of a hill, thereby 

 permitting no drainage from this infected stable to the other build- 

 ings. It was the duty of one man to care for these reactors, and he 

 was not permitted to mingle with the employees of the milking herd, 

 visit the stables, or to allow any interchange of utensils such as buc- 

 kets, forks, shovels, wheelbarroAvs, etc., from the infected stable to 

 any of the other stables. T shall refer to these reactors later in the 

 article, but will now ask your attention to the care of the milking 

 herd. 



The main milking herd was stabled in four barns, varying from 

 12 to 48 animals in each barn. Inasmuch as some reactors had been 

 found in every barn, a thorough disinfection of all stables was made. 

 The windows and doors of the barns were tightly sealed and the in- 

 terior filled with formaldehyde gas, the gas being generated by the 

 addition of potassium permanganate to formalin, and left sealed for 

 18 to 20 hours ; after which the doors and windows were opened and 

 the stable thoroughly aired. The wood work and iron stanchions 

 were washed with a solution of carbolic acid. The floors in all the 

 stables except one were of cement, and were flushed with a solution of 

 sulphate of iron and afterwards carbolic acid. A coat of whitewash 

 including 2 per cent, carbolic acid was applied to the ceiling and 

 walls. The manure was removed to the fields and the pit in which it 

 was stored was covered with chloride of lime. The policy of this 

 farm is not to pasture their milch cows, but to place them in a shady 

 exercising yard a portion of the day. This yard was scraped, remov- 

 ing several inches of earth, and then covered with lime. All utensils 

 around stables were disinfected. 



Even with the disinfection as outlined, it was believed that there 

 still might remain some possible points of infection in the stables 

 or exercising yards. Also it seemed reasonable to believe that some 

 non-reactors might carry within their body some tubercle bacilli 

 which had not as yet had time to produce a distinct tubercle and 

 Iherefore were incapable of giving a tuberculin reaction. 



The method outlined ai that time to eliminate all the suspicious 

 animals and keep the herd ifree from tuberculosis was as follows: 



First. All the animals in llie milking herd were to be tuberculin 

 tested every six months until two successive negative tests were ob- 

 tained and then yearly thereafter. 



Second. The calves that were intended to become future members 

 of the milking herd were to be immunized by the use of intravenous 

 injections of human tubercle l>acilli Avhich had been found by ex- 

 perimentation to be non -virulent for cattle. 



Third. All cows newly purchased before being allowed to enter 

 the main herd were to be placed in a quarantine stable about one hun- 



