350 STATE BOARD OF AGRICULTURE 



This animal died of general tuberculosis twenty-four days after inoculation. The 

 lungs, liver, spleen and lymphatic glands were thoroughly tuberculous. 



Guinea pigs, Nos. 128, 129 and 130 were each inoculated intra-abdominally with 5 

 c. c. of the same milk used in the case of 127, after it had been pasteurized. At the 

 time No. 127 died, these animals were chloroformed and carefully examined for 

 tuberculosis, but not a tubercle could be discovered. There were no indications of 

 tuberculosis whatever. 



Experiment 4. Guinea pig. No. 142. was injected intra-abdominally with 1 c. c. 

 of tuberculously infected milk from a source still different from experiments one, 

 two and three, and before it had been pasteurized. 



Four weeks later this animal died of general tuberculosis. Lungs and abdominal 

 organs, except the kidneys, as well as lymphatic glands, were in an advanced stage 

 of tuberculosis. 



Guinea pigs Nos. 13S and 139 were each inoculated with 5 c. c. of the same milk 

 used in the case of animal No. 142, after it had been pasteurized. 



These animals were chloroformed upon the death of pig 142, but no trace of tu- 

 berculosis could be detected upon close examination. 



Experiment 5. Guinea pig. No. 143, was inoculated intra-abdominally with 1 c. c. 

 of tuberculously infected milk before it had been pasteurized. The tuberculous 

 material was taken from a source still different from one, two, three and four. 



This animal died of general tuberculosis three weeks later; lungs, liver, spleen 

 and lymphatic glands were almost a mass of tubercles. 



When No. 143 died, Nos. 140 and 141 wei'e chloroformed. No tuberculous lesions 

 could be detected in either of them after much searching. 



In these five experiments, Nos. 44, 75, 127. 142 and 143 were each inoculated with 

 1 c. c. of tuberculously infected milk before it had been pasteurized; in each case the 

 tuberculous material used to infect the milk was taken from a diffei'ent source, 

 Every guinea pig inoculated with this material macerated in milk died a few 

 weelvs later, although the time from inoculation to death varied considerably. 



The above five animals acted as controls for Nos. 41, 42, 43, 76, 77, 78, 128. 129. 

 130. 138, 139, 140 and 141, which were inoculated with the respective samples of 

 milk, the same as were used with the five above, but after they had been pasteur- 

 ized. The amount used in these inoculations was five times the amount used for 

 the five controls. 



Every one of the controls died in the advanced stages of tuberculosis, while not 

 one of those receiving the pasteurized milk, even in quantities five times as great, 

 showed any trace of tuberculosis. Thirteen animals remained untouched by tu- 

 berculously infected milk subjected to a heat of 68° C. (155° F.) for twenty minutes. 



These experiments do not accord with Woodhead's, yet they give about the same 

 results as have been recorded by others. Whether it is possible to kill the tubercle 

 bacillus below 68° C. (155° F.), exposed for twenty minutes, is beyond our present 

 endeavor, since milk may be pasteurized at 68° C. without alteration or the pro- 

 duction of a cooked flavor. It is not best or essential that a lower point should 

 be adopted. As soon as a lower degree is considered, the greater and more com- 

 plicated Avill be the questions involved. From our own experience, we have found 

 that 60° C. (140° F.) for ten minutes will not kill the tubercle bacillus. This de- 

 gree and time have been used to kill other pathogenic germs in the presence of the 

 tubercle bacillus that the tubercle bacillus might be allowed to act upon animals. 

 This is a recognized method of operation when two pathogenic germs interfere with 

 each other. From 60° C. (140° F.) to 68° C. (155° F.) is a narrow range, and if it 

 were possible to raise the temperature a few degi-ees more without interfering 

 with the composition and quality of the milk, it would be advisable. If the taste 

 of American people could become accustomed to cooked milk, the matter of pas- 

 tetirization against pathogenic bacteria would be easily accomplished. 



Errors may creep into the process of pasteurization without notice. For this 

 reason some stress has been placed upon the uniformity of heating as is commonly 

 practiced. A receptalile containing the milk is placed in a pot of water and the 

 water raised to 68° C. (155° F.l. The milk is allowed to stand in the water for 

 twenty minutes, then cooled. The milk is usually covered and is not stirred during 

 the process. We have similated this crude method as closely as necesary to demon- 

 strate its worth. 



A dish 2% inches in diameter and holding 340 c. c. (a little over 11 oz.) was placed 

 in a water bath eight inches in diameter. The volume of water in the water bath 

 was made equal to that of the milk in the receptacle. The heat was applied and 

 during the process of heating the temperatures of the water and milk were taken. 



