No. 5. DEPARTMENT OF AGRICULTURE. 295 



open cases of tuberculosis, I mean cases where the lungs are affected 

 with the disease, the result of the invasion of the tuberculosis or- 

 ganism and that communicates with the bronchiae and bronchial 

 tubes and through the nose to the exterior and is capable of breath- 

 ing out the organisms. 



The CHAIRMAN: Is it possible for any one method to detect 

 all of them, Doctor? 



DR. GILL: Why, the tuberculin test comes the nearest and I think 

 that it gets nearly all with a very few exceptions, but when there is 

 an area in the lung, we will say, as large as that, located within 

 the chest and in a part of the lung that is remote from the free 

 surface of the ribs, it is almost impossible to get any sound that 

 would indicate that the cow had that lesion at that, or in that re- 

 mote part of the lungs, and many cases of tuberculosis that are 

 generalized are in such a state with the nodules, little grape-like 

 nodules, distributed all over the covering of the intestines and the 

 lining of the abdominal cavity, the covering of the pleura, the chest 

 and the heart sack, the pericardium just studded with tubercu- 

 losis nodules — those cases I have known to have been missed by the 

 so-called physical diagnostician, so that you see that it is not a real, 

 practical way of determining whether or not your cattle are affected 

 with tuberculosis. If you find one acute case, it is safe to say that 

 you have got more, there is no question about that, but I mean that 

 it is impossible to pick out all of the spreaders. 



Now, mind you, I am not speaking about all the cases, T say all 

 the spreaders, all the cases where there are lesions in the lungs 

 having a communication with the exterior. You know that cows 

 do not expectorate. You know that they have an accumulation of 

 mucus plus tubercular organisms in their throat, but instead of spit- 

 ting, they swallow. They swallow their excrementitious matter from 

 the throat and it might appear very funny to you for me to say that 

 a cow with an open lesion in the lungs would spread the disease 

 by spreading the organisms, but if you had seen, as I did at the 

 University of Pennsylvania — I think Dr. Marshall will bear me out, 

 and Dr. Pearson was there — some years ago they made a gauze 

 mask, put those masks over non-tuberculous animals and tuber- 

 culous animals and allowed the animals to breathe through this 

 gauze. Then they took the gauze to the laboratory and were sur- 

 prised themselves; I think they found the organisms in nearly every 

 instance, showing how the disease is disseminated, how quite pos- 

 sible it is for an animal to breathe out these organisms and if 

 breathed in by a neighboring cow which is in a susceptible condi- 

 tion, that cow would be affected. 



Now that brings up a point that always struck me from that 

 time, and I have applied it practically, and that is to have good ven- 

 tilation in a barn; not only good ventilation, but a constant dis- 

 turbance of the air, a current of air just to overcome that possi- 

 bility of the concentration of these exhaled organisms from an in- 

 fected animal, so that the air will disseminate them and lessen the 

 possibility of the other cows taking it. 



I don't know whether you follow me in that statement or not, 

 but there is ventilation and ventilation. You may have ventilation 

 enough but no current of air. You may have what you think in 



