194 STATE BOARD OF AGRICULTURE. 



to question this accepted belief; yet, from the present standpoint, bacter- 

 iologists in general adhere to the old work. 



There are, however, two methods by which milk may be contaminated 

 even in the secure gland, the udder: the one, when a cow is affected with 

 some bacterial disease; the other when bacteria find their way through 

 the milk duct of the teat into the milk sac at the base of the teat and 

 thus into the ducts which lead into the sac from the glandular sub 

 stance of the udder. 



In the discussion of the first method we are urged to consider tuber- 

 culosis, by its importance and the interest centered upon it at present. 

 In this dreaded disease, which causes tbe death of every eighth 

 person, the bacillus of tuberculosis may find its way into the milk if 

 present in the cow. This is more likely to take place if the disease is 

 located in the udder. In this case, tubercles formed by some process 

 of irritation of the bacillus, multiply in the tissue making the udder. 

 At first they are generally little hard nodules; but these keep enlarging 

 and eventually become soft, caseous and even purulent; a semi-fluid 

 pus is found in them. If one of these tubercles should be located 

 along any one of the numerous milk ducts leading to the milk 

 sac, and it should grow, finally breaking down into a purulent substance, 

 the contents of this tubercle with the thousands of tubercle bacilli 

 it contained would rush down the milk duct into the milk sac and would 

 thus contaminate the milk. We have supposed that the disease was 

 seated in the udder; is it possible if the disease is confined to the lungs 

 or other organs? We are permitted to answer only in the affirmative, 

 inasmuch as the bacilli have been found present in the milk when no 

 local lesions of tuberculosis could be discovered in the udder. Just 

 how they, the bacilli, reach the udder involves too many suppositions 

 and complications to even suggest in this place. When it is ascer- 

 tained how they make their journey from a tuberculous lung to the milk 

 gland, it will be time to discuss it, and it will then be simple to under- 

 stand. That the bacilli of tuberculosis may reach the milk in the udder 

 of a cow no matter where the disease is located in that cow is indisput- 

 able, having been established by competent workers. The per cent of 

 tuberculous cows giving tuberculous milk varies from a very low figure 

 to a very high or startling figure, consequently, the milk of tuberculous 

 animals is dangerous. 



The other method of contaminating the milk in the udder is through 

 the milk duct of the teat. Although apparently closed to all foreign 

 substances, it nevertheless fosters hosts of bacteria. For some time 

 past, bacteriologists have been reporting the number of bacteria found 

 in the "fore" milk, "middle'' milk and strippings. Invariably they find 

 the most to abound in the "fore" milk. The first milk drawn from a 

 cow washes out the ducts and leaves few bacteria to infect the "middle" 

 milk and strippings. In another way the duct may be demonstrated 

 to be burdened with bacteria. Disinfect the udder and teats with as 

 much care as possible, introduce a sterile milk tube connected with 

 a sterile flask closed with cotton wool into the milk duct, and the 

 milk after standing in these flasks for some time will show the presence 

 of bacteria. Out of twenty-eight samples obtained in this way the 

 author obtained only two which were sterile. In a very few of these 

 samples, several weeks were required to show any change whatever. 



