BACILLI IN CHRONIC INFECTIOUS DISEASES. 375 



pathologists were quite prepared to accept it. The more conservative 

 have since been obliged to yield to the experimental evidence, which 

 has received confirmation in all parts of the world. To-day it is 

 generally recognized that tuberculosis is a specific infectious disease 

 due to the tubercle bacillus. 



As evidence of the thorough nature of Koch's personal researches 

 in advance of his first public announcement, we give the following 

 resume of his investigations : 



In nineteen cases of miliary tuberculosis the bacilli were found in 

 the tubercular nodules in every instance ; also in twenty-nine cases 

 of pulmonary phthisis, in the sputum, in fresh cheesy masses, and in 

 the interior of recently formed cavities ; in tuberculous ulcers of the 

 tongue, tuberculosis of the uterus, testicles, etc. ; in twenty-one cases 

 of tuberculous scrofulous lymphatic glands ; in thirteen cases of 

 tuberculous joints ; in ten cases of tubercular bone affections ; in four 

 cases of lupus ; in seventeen cases of Perlsucht in cattle. His ex- 

 perimental inoculations were made upon two hundred and seventy- 

 three guinea-pigs, one hundred and five rabbits, forty-four field 

 mice, twenty-eight white mice, nineteen rats, thirteen cats, and upon 

 dogs, pigeons, chickens, etc. Very extensive comparative researches 

 were also made, which convinced him that the bacillus which he had 

 been able to demonstrate in tuberculous sputum and tissues by a spe- 

 cial mode of staining was not to be found in the sputa of healthy 

 persons, or of those suffering from non-tubercular pulmonary affec- 

 tions, or in organs and tissues involved in morbid processes of a 

 different nature. 



53. BACILLUS TUBERCULOSIS. 



Discovered by Koch (first public announcement of discovery 

 March 24th, 1882). The bacilli are found in the sputum of persons 

 suffering from pulmonary or laryngeal tuberculosis, either free or in 

 the interior of pus cells ; in miliary tubercles and fresh caseous 

 masses, in the lungs or elsewhere ; in recent tuberculous cavities in 

 the lungs ; in tuberculous glands, joints, bones, and skin affections 

 (lupus) ; in the lungs of cattle suffering from pulmonary tubercu- 

 losis Perlsucht ; and in tubercular nodules generally in animals 

 which are infected naturally or by experimental inoculations. 



In the giant cells of tubercular growths they have a peculiar and 

 characteristic position, being found, as a rule, upon the side of the 

 cell opposite to the nuclei, which are crowded together in a crescentic 

 arrangement at the opposite pole of the cell. Sometimes a single 

 bacillus will be found in this position, or there may be several. 

 Again, numerous bacilli may be found in giant cells in which the 

 nuclei are distributed around the periphery. They are more numer- 



