MICROBES AS FACTORS IN SOCIETY, 107 



order. The poor man, by different forms of inanition, overwork, 

 exposure, or uncleanliness, is liable to derangements of the lungs, 

 liver, kidneys, bowels, etc. Like the rich man, he has a pathology 

 special to certain organs, and different from that of the other, but 

 which is due to his social sanitary situation. 



The professions also entail their special maladies, which are 

 liable to infect those who exercise them. Lead chemically poisons 

 those who handle it painters, printers, white-lead makers, etc. 

 and mercury is dangerous to silverers of glass and gilders ; while 

 each poison affects particular organs most directly lead the 

 kidneys, bowels, and brain, mercury the brain and nerves. Ex- 

 amples might be multiplied to show how the profession may 

 injure the organs, create real diseases, or induce an imperfect con- 

 dition of health which will facilitate the invasion of the microbe. 

 It is not necessary to dwell here on the pathogenic effects of alco- 

 holic intoxication a condition which is in every feature the 

 product of social influences. It ravages all classes of society, 

 and is illustrated in the most various pathological modalities. 



In short, we find that a great multiplicity of mechanisms, all 

 of social origin, may affect the internal organs in their structure 

 or their work, and bring the person into a condition of receptivity 

 to microbes. A thousand social conditions may expose us to the 

 invasion of microbes and thus make real the second term required 

 to constitute an infectious disease. The hostile microbe is in fact 

 everywhere within and without us, seeking, we might say, what 

 it may devour. All the natural cavities of the body the nose, 

 the mouth, and the digestive tube having exterior openings are 

 seeded with microbes brought from without by air or food, and 

 afterward multiplied. The skin is similarly exposed. Among 

 these microbes there are also others, the relics of infectious dis- 

 eases, with which the subject, now well, has been formerly at- 

 tacked. All these microbes live in the normal condition of a 

 later life ; they are sometimes useful, as we have seen in regard 

 to digestion ; more frequently inoffensive in the face of the resist- 

 ance opposed to them by the cellular coverings of the organic 

 cavities or by the activity of those zealous defenders of the organ- 

 ism, the white globules, or by the chemical action of the organic 

 liquids. But when the texture of these coverings is modified by 

 some of a variety of circumstances, whether of external or of in- 

 ternal origin, or when one or more of the microbes attain an 

 unusual degree of virulence, then the protective barriers will 

 be overcome, the microbe will penetrate to the interior of the 

 tissues, and will be able to bring on some of a great variety 

 of diseases, from pneumonia to erysipelas, meningitis, or liver 

 disease. 



The microbes living without the organism are likewise of 



