342 TUBERCULOSIS AS A TYPE OF BACTERIAL DISEASE 



human consumption. This was injected into the peritoneal cavity of a healthy calf. 

 The animal became ill and died forty-two days after inoculation from pycemia (blood- 

 poisoning). On post-mortem examination it was found that there were abundant 

 signs of generalised tuberculosis.* This calf was not tested with tuberculin pre- 

 viously to the experiment. Professor Sidney Martin carried out a number of 

 experiments for the Royal Commission on Tuberculosis,! amongst which three out 

 of four calves fed on human tuberculous sputum contracted the disease. 



Iii 1902 Koch again emphasised the comparative rarity of primary 

 intestinal tuberculosis in the human being, and the local, as 

 distinguished from the general, infective nature of accidental bovine 

 inoculation of man (tuberculosis verrucosa cutis). In isolated cases 

 the nearest lymph glands might become affected, but the disease 

 remained nevertheless a local one. Dr Koch further expressed the 

 view that if bovine tuberculosis was transmissible to man by means 

 of the milk of cows with tuberculous udders, it would be reasonable 

 to suppose that "groups of illnesses" would occur, in a manner 

 analogous to other infective diseases, though the circumstances would 

 differ owing to the different length of the incubation periods. By 

 way of illustrating the non-infectivity of bovine tubercle bacilli 

 conveyed by milk, Koch points out (a) that bovine tubercle bacilli 

 must be taken into the human system very frequently, as 1 to 2 

 per cent, of all milch cows surfer from tuberculous udders ; (b) that 

 in addition to being drunk in considerable quantity and for long 

 periods, such milk is also widely distributed; (c) that domestic 

 sterilisation of milk does not occur to any appreciable extent ; (d) 

 that the same may be said of the large dairies ; and finally (e) that 

 if milk under such circumstances is dangerous, the butter derived 

 from it will also be dangerous. For these reasons he maintained 

 that any resulting disease must be widespread. Yet Koch has found 

 "instead of the countless cases," which we ought to expect, "two 

 groups of illnesses and 28 isolated cases of illness." On examina- 

 tion he finds most of these recorded cases not free from objection. 

 To carry conviction as to milk-borne tuberculosis, Koch maintains, 

 that the following conditions must be fulfilled: (i.) Certain proof 

 of tubercle in the person affected; (ii.) exclusion of other sources 

 of infection ; (iii.) the condition of all the consumers of the suspected 

 milk; (iv.) the exact source of the suspected milk, particularly in 

 respect to the disease of the udder of the cow yielding the milk. 

 Finally, he concludes that all that can be said at present is that the 

 injurious effects of rnilk infected with bovine tuberculosis and its 

 products are not proven. 



On the other hand, many other workers have been investigating 



* Bacterioloyi/ and Infective Diseases Edgar M. Crookshank, 1896, pp. 389-391. 



f Report of the Royal Commission appointed to inquire into the Effect of Food 

 derived from Tuberculous Animals on Human Health, 1895, part iii., Appendix, 

 pp. 18 and 19. 



