126 AiSTNTJAL REPORT OF THE Off. Dod. 



heifer calf born from a tuberculous cow in the experimental herd. 

 It was vaccinated four times in September, October, November and 

 December 1DU8. This calf was kept with its tuberculous mother un- 

 til it was well grown and and was also in association with highly 

 tuberculous cattle. She was bred early and calved at about 22 

 months. She had a second calf 11 months later. During last Au- 

 gust, resulting from an attack of cowpox, one teat closed and the 

 milker attempting to open it with a milking tube caused an infection 

 of the udder which resulted in gangrene and death. The postmor- 

 tem examination shov\-ed ail of the organs to be free from tubercu- 

 losis excepting that in a few of the lymphatic glands of the intestines 

 there were some calcified, healed tubercules, appearing as small 

 stone like masses enclosed in a dense fibrous envelope. There can 

 be little doubt that this cow sustained an infection as a calf, before 

 it w^as protected by vaccination, and while feeding on the milk of 

 a tuberculous cow, that it fully recovered from this infection, for 

 only the scars remained, and that in spite of rearing two calves 

 before she was three years old and in spite of her constant exposure 

 under conditions that has led to the infection of all unvaccinated cat- 

 tle and to the death of some, she has proven wholly resistant to tu- 

 berculosis three years after vaccination. 



''Not one animal that has been vaccinated in accordance with the 

 method that we are now using in practice and that I have outlined 

 has become tuberculous from natural exposure to the disease, nor 

 has an animal been injured by vaccination. 



"With such evidence, covering four years and a large number of 

 cattle we have felt that we are amply justified in recommending vac- 

 cination and in applying it in practice. 



''The State Livestock Sanitary Board is a very conservative body 

 and it has not endeavored to at once launch this new method in 

 wholesale fashion. On the contrary, it is planned to introduce it 

 gradually, using it at first where it is most needed and where the 

 conditions are such as to give it a fair trial. Because the method is 

 new and only those engaged in our experimental work have had ex- 

 perience in handling it, it is for the present applied only by specially 

 trained men from the State laboratory. Cattle have been vacci- 

 nated in nearly all parts of the State and the method is having a 

 chance to prove its worth under widely varying conditions. No un- 

 expected or unpleasant results have been observed or reported. 



"For the present only young cattle are being vaccinated, calves 

 and heifers to within six months of calving. The reason for this 

 is that the vaccine consists, as has been explained of living tubercle 

 bacilli of human type. It is not known how long these germs will 

 live in the system of the vaccinated animal. As they are not capa- 

 ble of causing infection it is highly probable that they disappear 

 from their bovine host within a short time, within two or three weeks 

 at most, but until there is more positive evidence on this point, it is 

 not deemed justifiable to vaccinate cow^s in milk or cows that are 

 soon to produce milk. In principle and in practice the process is 

 otherwise as applicable to mature cows as to calves, provided the 

 cattle are tested and are found to be free from tuberculosis before 

 they are vaccinated. 



"Some of our experiments show that vaccination has a marked 

 curative tendency on animals already infected. But while it is being 



