quantity. (Schottelius, by the way, has since acquiesced 

 in the infectiousness of tuberculosis.) Weichselbaum 

 found a few similar nodules in the lungs of one of three 

 dogs treated in this way, but no tuberculosis. He found 

 further, that the inhalation even when brief, of phthisi- 

 cal sputum induced general tuberculosis ; but after boil- 

 ing, or after treatment with corrosive sublimate, the same 

 sputum produced no tuberculosis, and rarely if ever 

 nodules. 



These inhalation experiments of Tappeiner, Bertheau, 

 Schottelius, and Weichselbaum illustrate admirably from 

 the experimental side what had been for years acknowl- 

 edged from the histological standpoint : that there is 

 nothing characteristic in the individual nodule. The 

 same histological structure, including the giant-cell, may 

 be found in the nodules of syphilis or lupus, as well as 

 of tuberculosis ; the same local anatomical change may 

 follow the inhalation of large particles of Limburger 

 cheese, as the inspiration of atomized phthisical sputum. 

 For decades the pathologists from Virchow down, their 

 eyes full of caseous matter and giant-cells, wrestled with 

 one another over the question, what is true tubercle? 

 Their hair-splitting disputes remind us of the bitter con- 

 troversies of the mediaeval philosophers as to how many 

 spirits could stand on the po.int of a needle. Finally it 

 dawned upon them they were confounding anatomy with 

 etiology ; they were regarding as characteristic of one 

 morbid process a histological structure common to sev- 

 eral ; they were ascribing to a single cause the common 

 effect of many ; they were confounding tubercle with tu- 

 berculosis. As Cohnheim said years ago : " Struggle 

 against this as we may, there is no help for it the ana- 

 tomical definition suffices no longer for the tubercle and 

 tuberculosis." Even Schottelius, the last of the German 

 pathologists to deny the infectiousness of tuberculosis, 

 has finally recorded his conviction that tuberculosis is 

 certainly infectious, though not all individual tubercles 

 belong to tuberculosis. 



And what shall be considered a tuberculous tubercle ? 



