io 4 THE POPULAR SCIENCE MONTHLY. 



sumption the bacillus finds its food prepared for it in the unhealthy 

 state of the blood and tissues altered by the poisons that have 

 been rebreathed from foul air so also must it be in pneumonia ; 

 if we are to accept the statements made about the bacterium of 

 pneumonia (Crookshank, page 273). Secondary pneumonia, which 

 is a lung attack resulting from the poison in the system from 

 such a fever as typhoid, throws some light upon this matter, and 

 seems exactly to explain the origin of ordinary pneumonia. In 

 ordinary pneumonia we believe that it would be found that the 

 person attacked had been living in rooms where the air was 

 tainted, had breathed consequently, again and again, the exhaled 

 poisons, until these poisons had so altered the tissue as to allow 

 the bacterium to form its lodgment ; in other words, that he was 

 as much " poisoned " as the person suffering from secondary pneu- 

 monia. Of course a slight chill, by arresting the action of the 

 skin and thus increasing the poison in the system, is likely enough 

 to be the immediate precursor of the attack by rendering the con- 

 ditions still more favorable for the germ. Again, latent pneu- 

 monia in quite young children is sometimes masked (Quain, page 

 880) by the signs of the nervous disorder which precedes it. This 

 nervous disorder tells the story. It is caused by the poisons 

 which are acting on the system, and which at last produce the at- 

 tack of pneumonia.* 



It might, however, be urged that a person leading a healthy 

 outdoor life might, after severe exposure, be attacked by pneu- 

 monia. Certainly, and in his case the attack would mean poison- 

 ing (that is, predisposing for the germ by poisoning) through the 

 skin ; just as in the case of the man living in bad air it would 

 mean poisoning through the air taken into the lungs. 



Now, granting that this is a true explanation, that pneumonia, 

 or even common cold, is a case of poisoning, and only a case of 

 cold in a secondary sense, it is worth noticing that the effect of 

 these poisons must be felt in the throat and bronchial passages 

 and lungs much more than in other organs. These poisons would 

 cling to the sides of the throat and bronchial (and nasal) passages, 

 and would often enter the lungs. In the case of persons living in 

 foul air, these organs, being more exposed and in intimate contact 

 with the poison, would probably be saturated with it, and there- 

 fore would be always prepared for disease. We can then under- 



* If on the other hand it is believed that pneumonia can arise without the intervention 

 of the bacterium, we must regard it as a case of direct instead of indirect poisoning. That 

 there is such direct poisoning we know from those attacks of the liver and kidneys which 

 follow a severe chill, and throw back the poisons, which should have been excreted by the 

 skin, on to those organs. Parkes (p. 164) strongly believed that bronchitic affections are 

 often produced from the breathing of foul air. He does not, however, as far as we are 

 aware, enter into explanations. 



