THE PRESENCE IN MILK OF CERTAIN ORGANISMS 245 



to be non-pathogenic, while others were found to be virulent. No 

 cultural characteristics appear to afford a definite distinction 

 between the virulent and the non-virulent strains. 



It is probable that a number of the strains of these bacteria give 

 rise to no symptoms when taken into the animal organism by the 

 mouth. There is, however, abundant evidence to show that some 

 strains have a high degree of virulence for human beings, and that 

 many epidemics, generally of sore throats, have been produced 

 by drinking milk containing such streptococci. The history of 

 the epidemics which occurred in America, and were fully investi- 

 gated, in the years 1911-12, leaves no doubt on this matter, and 

 the epidemics recorded in our own country afford evidence in support 

 of these facts. 



Tubercle Bacilli. There is no need at the present day to bring 

 forward evidence in regard to the presence of bovine tubercle 

 bacilli in milk. Its occurrence in a large number of samples of the 

 general milk supply has been demonstrated beyond doubt both 

 in this and in other countries. Further, there can be no reasonable 

 doubt that such bacilli of bovine origin are pathogenic to young 

 children. The findings both of the Royal Commission on Tuber- 

 culosis and of other observers show that children suffer from disease 

 caused by the tubercle bacillus obtained from cattle, and that the 

 percentage of tubercular disease in children which is caused by the 

 bovine tubercle bacillus is high. On the other hand, the percentage 

 of this disease caused by the bovine tubercle bacillus in adults is 

 very low. 



Investigations have shown that the bacilli, when taken in with 

 food, can pass through the walls of the alimentary canal and reach 

 the neighbouring glands, where they develop and spread to further 

 parts of the glandular system and to other organs, ultimately 

 causing generalised tuberculosis. It has been shown that the main 

 source of infection by bovine tubercle bacilli must be by means of 

 milk which contains these organisms. The argument that if 

 these organisms are harmless, or comparatively so, to adults, they 

 are not harmful to children, cannot be regarded as having any 

 weight. It is well known that children are susceptible to patho- 

 genic influences which leave an adult unaffected. 



Other Organisms. Other organisms occur in milk when the 

 cow or other animal supplying the milk is suffering from disease 

 caused by such organisms. Thus, cows which have been infected 

 by the Bacillus abortus continue to excrete these organisms for 

 prolonged periods after such infection has occurred. The organisms 

 are also passed out in the milk, in many cases before evidence of the 

 infection by this organism has been demonstrated clinically. 



^A consideration of the presence of the organism of Malta fever 

 in'the milk of goats is beyond the scope of this work, but is in- 

 teresting in view of the analogy which it presents to the^conditions 

 here under review. 



