230 PATHOGENIC BACTERIA IN MILK 



' strumous ' glands of children and young adults. Lastly, from 

 feeding there may be affection of the lymphatic glands alone." 



2. Four calves received at one meal, mixed with their food, 

 about I kilogramme of bovine tuberculous material. They all 

 contracted tuberculosis. Dr Martin further pointed out that 

 although " from feeding calves with bovine tuberculous material 

 a lesion in the form of nodules is produced in the intestine, it may 

 not proceed to ulceration but remain stationary. The intestine is 

 affected in the form of isolated nodules as early as four weeks after 

 feeding. . . . The mesenteric glands are in all cases affected to a 

 greater or less degree. From the intestinal lesion the disease in 

 calves spreads to the lymphatic glands in the thorax and the lungs 

 or pleura, or both of these." 



3. Four calves received at one meal, with their food, 70 c.c. of 

 sputum (containing a large number of tubercle bacilli) from two 

 cases of human consumption. Three of these calves contracted 

 tuberculosis, but in none of them was there any sign of disease 

 except nodules in the intestine, and in the fourth calf every organ 

 and gland was healthy. Two calves received 440 c.c. of human 

 sputum containing a large number of tubercle bacilli. One calf 

 contracted tuberculosis of the intestine and mesenteric glands. 

 The other remained perfectly healthy. Dr Martin concludes that 

 " it is evident, therefore, that in the case of human tuberculous 

 sputum we are dealing with material which is less infectious to 

 calves than bovine tuberculous material. This lessened infectivity 

 is possibly not merely a question of dosage, but one of diminished 

 activity of the tubercle bacilli in sputum as compared to its activity 

 in the tuberculous lesion of the cow." ^ 



^ Various circumstances have in all probability contributed to render un- 

 successful or irregular in result the numerous feeding experiments which have 

 been made. The tissues of animals differ greatly in susceptibility to tubercu- 

 losis ; and the virulence of the infective material itself varies enormously, as 

 does the virulence between different generations or races of tubercle bacilli. 

 Hence it comes about that one animal may eat with its food a certain amount 

 of tuberculous material and yet not develop tuberculosis, whilst another animal 

 of the same species might quickly develop the disease, which would in all 

 probability show itself at the animal's weakest point, and not always necessarily 

 in the intestine. Again, there is the question as to what constitutes a positive 

 effect of inoculation and as to whether or not there has been made a micro- 

 scopical study of the viscera and glands. Further, there is another point 

 which should not be overlooked, namely, the subsequent treatment of the 

 inoculated animal. Whilst it is essential to prove that the animal to be inocu- 

 lated is free from tuberculosis, it should be remembered that in taking very 

 healthy animals for experiment, and in subsequently treating them in what 



