from some Old Tuberculous Lesions in Man. 537 



time found in the bodies of those who died from other causes, and 

 not a few of these have been found to be non-infective. These ob- 

 servations seem to me to be worth recording as a contribution to 

 the data from which one may estimate the duration of the vitality 

 of tubercule bacilli in the bodies of living animals, and because 

 our views about the practically important question of the origin of 

 phthisis must be largely determined according to the conclusion 

 we come to as to the vitality of the bacillus. If any considerable 

 proportion of these lesions are really not capable of infecting then 

 the great frequency with which they are present is not so strongly 

 in favour of latency as it is usually held to be. 



The first case investigated by me was that of a child of eight, 

 who died of diphtheria. Quite unexpectedly, at the post-mortem 

 examination, was found a mass of enlarged mesenteric glands, four 

 of which were caseous and softened at their centres. There was 

 ample material for the purpose of inoculation and I was able to 

 make as much as 25 c.c. of a creamy emulsion, in which as many 

 as 170,000 tubercle bacilli per cubic centimetre could be seen. 

 The whole of this emulsion was injected into two calves, two 

 rabbits and two guinea-pigs, but not even the latter developed 

 any trace of tuberculosis. 



Naturally I considered the result suspicious, and every sug- 

 gestion probable and improbable was considered which might 

 account for it, without having to suppose that the bacilli were 

 dead ; but without success. It was even thought that diphtheria 

 toxin might be fatal to tubercle bacilli, but this was tried and 

 found not to be the case. 



The next case was one in which tuberculous glands were re- 

 moved by operation from a child of a little under four years of 

 age. Fifteen months previously some glands had been removed 

 from this child and sent to me, and proved to contain numerous 

 virulent tubercle bacilli of the bovine type. The glands removed 

 at the second operation contained two as large as ripe gooseberries, 

 which were caseous and softened. An emulsion was made in the 

 usual way and injected into guinea-pigs, but the animals remained 

 unaffected, and cultures attempted from the emulsion failed to 

 grow any tubercle bacilli. 



The next case was one of tuberculosis mainly affecting the lungs 

 and pleura of a child of eight. The bronchial glands were en- 

 larged, and three contained small caseous foci, another contained 

 a larger mass of the same material ; a guinea-pig injected with 

 all the caseous material which could be obtained from these glands 

 remained unaffected. No tubercle bacilli were seen in the emulsion 

 prepared for injection. 



The fourth case was one of localised tuberculosis in a boy of 

 fourteen. After a slight injury to the hand, which was slow in 



