296 BULLETIN No. 161 [November, 



It appears that tubercle bacilli, especially in sputum and other 

 mucoid material, withstand desiccation better than other nonspore- 

 formers. The difference is not great and there are many apparent 

 exceptions where other nonspore-bearers live for a very long time, 

 like the one given above after Harding and Prucha 54 . Diplococcus 

 pneumonia has been reported as living for 192 days when dried 

 on silk (Sirena and Alessi 135 ). 



The important fact which has been so thoroly established in 

 recent years is that tuberculous sputum reduced to dust causes 

 tuberculosis when experimental animals (guinea pigs, rabbits, cats, 

 dogs and calves) are made to breathe such dust-laden air. How 

 great the danger is to man and cattle to breathe dried tuberculous 

 material is yet a disputed question. In 1882 Koch, in his work 

 on "Die Aetiologie der Tuberculose", pointed out that dried tuber- 

 culous sputum is one of the most important factors in causing 

 tuberculosis. It was not until 1905 when the work of Calmette 

 and Guerin 21 was published that ingestion was brought forward 

 as a very important factor in producing tuberculosis. It was sug- 

 gested by the advocates of this theory that practically all tubercu- 

 losis is produced by ingestion that even inspired material is swal- 

 lowed and what apparently is inhalation tuberculosis is actually 

 tuberculosis by ingestion. This conclusion will not hold in the 

 light of the most recent experiments, especially those carried out 

 at Breslau and collectively published by Fliigge 40 (1908), "Ver- 

 breitungsweise and Bekampfung der Tuberkulose". It is shown 

 here that in all animals with which experiments have been made 

 it required a hundred to a thousand times more tubercle bacilli to 

 produce tuberculosis by feeding than it does by inhalation. So the 

 thought that the swallowing of a part of the few tubercle bacilli 

 necessary to produce tuberculosis by inhalation is the cause of in- 

 gestion tuberculosis is wholly precluded. 



A complete discussion of this most interesting subject cannot 

 be given here. The data in the two following tables show the fact 

 mentioned above, that it requires many times more germs to pro- 

 duce tuberculosis by feeding than by inhalation ; also another most 

 important fact, that severe tuberculosis may be produced by either 

 method of infection. It must not be understood that the facts 

 exhibited in these two tables in any way indicate which is the 

 more frequent method of infection. For what matter if it does 

 require one thousand times more tubercle bacilli to produce tuber- 

 culosis, by feeding than by inhalation, who knows whether we are, 

 on the average, taking in one thousand times more of these germs 

 in the food than in the breath? 



On one hand, Calmette 19 is found declaring that "In the ordi- 

 nary daily life, the infection of the digestive^ organs is predomi- 



