EXPERIMENT STATION BULLETINS. 321 



culosis through wounds, through careless use of instruments, by sleeping in a room 

 previously occupied by a tuberculous subject, through infected clothing, by sexual 

 congress when the generative organs are involved. 



THE PATH OF TUBERCULOSIS IN TIIi: BODY. 



When the germ has located itself in one part or the other of the body, there is a tub- 

 ercle formed at that point and the virus probably does not leave this place until the 

 tubercle begins to disintegrate. Then the virus apparently follows the lymphatic chan- 

 nels and the disease may be distributed to various parts of the body. If a guinea pig is 

 inoculated subcutaneously in the side and the various stages of development are noted 

 as the disease advances, it will be found that a tubercle has developed at the point 

 of inoculation first and that the gland nearest to the point of inoculation next becomes 

 affected. If the inoculation happens to be nearest the inguinal region, the inguinal 

 glands are first affected; if nearest the axillary region, the axillary glands are 

 first aflected; if the inoculation is over the abdominal cavity, there is a gradual 

 penetration of the disease and the infection is carr-ied to the lymphatic glands and 

 mesenteric glands of this cavity; if the inoculation is over the thoracic cavity, the 

 virus may penetrate to this cavity and involve the bronchial, the mediastinal glands and 

 the lungs. Sometimes, however, the axillary and inguinal glands on the opposite 

 side of the body become aff'ected before and simultaneous with the entrance of the 

 disease to the thoracic and abdominal cavities. 



If the virus is introduced into the abdominal cavity or into the thoracic cavity, 

 the disease frequently advances so far as to kill the animal before it advances from 

 the cavity into which it was introduced. Yet it is a common thing for the disease 

 to pass from the abdominal cavity into the thoracic cavity or from the thoracic cavity 

 into the abdominal cavity, when either the abdominal or thoracic cavity respectively 

 receives the virus. 



When the virus is taken through the mouth by means of food as in the case of 

 feeding swine, the disease is first apparent in the mesenteric glands, from which it 

 seems to spread to the liver and spleen, and finally makes its way toward the thoracic 

 cavity. This is the usual path we have found by inoculation according to this 

 method. However, this path is not always strictly adhered to. The pigs in consuming 

 inoculated food sometimes inoculate themselves through the thoracic tract. At such 

 times, the glands and lungs of the thorax first become involved and so rapidly develop 

 the disease that the pig dies before there is much evidence of it in the mesenteric 

 glands, where we would expect to find the first traces of the disease. 



Of course when the virus is introduced through respiration, the disease usually 

 makes all its progress in the lungs and neighboring glands. One of the first pair of 

 glands to show the disease, and perhaps where the disease is as commonly found as 

 anywhere, is the posterior pharyngeal glands. I have noticed the affection of these 

 glands where tuberculous lesions were found elsewhere, only in the thoracic cavity and 

 also only in the abdominal cavity. This would indicate that these glands are as prone 

 to infection through the ingestion of food as through the ingestion of the virus by 

 respiration. When the disease enters the thoracic cavity, the posterior mediastinal 

 glands are among the first to show signs of tuberculosis, then follow the bronchial 

 glands and the lymphatic glands throughout the lung tissue. Deviations from this 

 path of infection are frequent. 



The significance of the paths taken by the virus in its distribution throughout the 

 body and the production of generalized tuberculosis appears to place the responsibility 

 of conveying the tubercle bacilli from one part to another upon the lymphatic chan- 

 nels. This is borne out by the usual development of the disease in those organs con- 

 tiguous to the one already aff'ected. It may be that the blood vessels enter into this 

 function of a virus carrier more pro**inently than we suspect, still there is little 

 known that would support this view. 



GEOGRAPHICAL DISTRIBUTION OF TUBERCULOSIS. 



So generally distributed all over the world is this disease that to arrive at or even 

 hypothetically draw definite conclusions would perhaps be bold. I desire more to 

 offer a suggestion or two than to put anything into the form of a positive statement. 



Authentic history does not tell us very explicitly where the home of this disease 

 was originally, but there appears to be sufficient data to make central and southern 

 Europe the place from which this trouble has radiated to various parts of the world. 

 The Danes believe that they have brought tuberculosis into Denmark by means of 



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