INTERCOMMUNICABILITY 341 



2. That in specially prepared and suitable media artificial cultures of the tubercle 

 bacillus from bovine and human sources have produced indistinguishable effects 

 when they have been employed to infect a variety of animals, which would seem 

 to indicate that the conditions produced are only variations of one and the same 

 disease. 



3. That tuhereulin * produces a specific reaction in tuberculous cattle, whether 

 human or boyine- tubercle bacilli have been employed in its preparation. — (Mac- 

 Fadyean.) 



[It will be seen that these three reasons have relation to the theory of the identity 

 of bovine and human tuberculosis.] 



4. That because the tubercle bacillus derived from bovine sources is, either by 

 inoculation or ingestion as food, admittedly very virulent and dangerous for such 

 diverse species of animals as the rabbit, horse, dog, pig, sheep, and cow, it is 

 highly probable that it is also dangerous to man.f For ib is well known that the 

 majority of disease-producing bacteria are harmful to only one or two species of 

 animals, but those disease-producing bacteria that are common to all the domesticated 

 animals are also able to produce disease in man. 



.I. That the statistics and percentages set forth by Dr Koch with regard to 

 primary intestinal tuberculosis cannot be accepted as representing universal 

 experience. For example, in two separate reports from two children's hospitals in 

 London and Edinburgh dealing with 547 cases of deatli from tuberculosis in children, 

 it appears that 29 -1 per cent and 28 •! per cent, of the cases respectively primary 

 infection appeared to have taken place through the intestine. But quite apart from 

 statistics, the whole question of such primary intestinal tuberculosis (which Dr 

 Koch held as the only acceptable evidence of tuberculous infection through milk 

 and meat) is fraught with many difficulties and fallacies, and is at present sub jwdice. 

 It has been shown by Professor Sidney Martin and others that primary intestinal 

 tuberculosis may not be, by any means, an invariable criterion of tubercular infection 

 by means of food {vide infra). 



6. That there are on record a number of cases in which there appeared to be 

 substantial evidence to show that persons had contracted tuberculosis, directly or 

 indirectly, by means of milk or meat. It is obvious that such cases, unless occurring 

 with extraordinary frequency, are only of relative value. Moreover, there are other 

 channels of infection to eUminate, and this it is often impos.sible to do. 



7. That the results obtained from the inoculation of human tubercle into animals 

 by Dr Koch cannot be accepted as in complete accord with universal experience. 

 In England alone somewhat similar experiments have been performed, having positive 

 results. Several years ago Professor Crookshank carried out such an experiment. 

 He obtained sputum containing numerous tubercle baciUi from an advanced case of 



* Tuberculin is a product of tlie artificial cultivation of the tubercle bacillus (human 

 or bovine) now used as a diagnostic injection test into cattle. If such cattle are 

 suffering from tuberculosis they " react " (giving high temperature, sweUing at the 

 point of inoculation, etc.) ; if not so suffering, they do not react. 



t See the researches of Villemin (1865), Klebs, Chauveau(1867), Gerlach, Giinther 

 and Harms (1870-1873), Bollinger, and others. Further, Fn'edberger and Frohner 

 state in their Veterinary Pathology that Wesener compiled reports up to 1884 of 369 

 feeding experiments, the positive and negative results of which were about equal in 

 number. From this compilation it appears that (a) 71 animals, among which guinea- 

 pigs and swine proved most susceptible, were experimented upon with human tuber- 

 cular matter ; (6) 180 experiments were made with tubercular matter from cattle ; 

 (c) the flesh of tuberculous cattle was given on 32 occasions as food, with the result 

 that pigs were found to be more susceptible than other animals, and that dogs were 

 unaffected ; and {d) the milk of tuberculous cows was given as food in 86 cases. 

 From these experiments it was found that in the scale of comparative racial sus- 

 ceptibiUty the herbivora (cattle, sheep, goats) proved highest, then swine, and after 

 these guinea-pigs and rabbits. Carnivorous animals were little affected. Bovine 

 tubercular matter was found to possess the greatest power of infection, then came 

 the sputum of tuberculous men, then the milk of tuberculous animals, and lastly, 

 tuberculous flesh. 



