ATMOSPHERE IN RELATION TO HUMAN LIFE AND HEALTH. 251 



Part II. — Climate, Air, and Health. 



MALARIOUS AND INFECTIOUS DISEASES: THEIR CONNECTION WITH 

 AND DESTRUCTION BY THE ATMOSPHERE — THE INFLUENCE OF 

 CLIMATE ON NATIONAL HEALTH. 



The spreading, infectious, or epidemic diseases in the animal world 

 and in mankind depend to a very great extent upon aerial influences. 1 

 Microscopic fungi or microbes, the prime causes of these disorders, are 

 sensitive to dryness, moisture, heat, cold, and sunlight, and a study of 

 their relations to the atmosphere has led and will lead to results of the 

 very highest importance to human welfare. Many of them reach the 

 living body, upon which they lodge, through the air; many are partly 

 nourished outside the body by the gases and moisture which the air 

 brings to the seat of their growth. But as a whole the pure atmosphere 

 works energetically and unceasingly for their destruction ; dry air and 

 sunlight deprive most species of disease organisms of their vitality. 

 This great generalization may best be appreciated by a brief review 

 of the principal endemic, epidemic, and pandemic maladies to which 

 the human race is subject, dealing especially with the manner in which 

 they are developed, restrained, diffused, or annihilated by the qualities 

 of the air. 



Microbes have been divided into two main classes, aerobic and 

 anaerobic, the first growing best in the presence of air and the second 

 growing best in substances and in positions to which free air has no 

 access. 



Some of the first class, such as the hay bacillus (subtilis), grow best 

 only with a copious supply of air ; some grow better when the air sup- 

 ply is not large than when free air is admitted ; some of the second 

 class can grow in the absence of free air, but thrive more when some 

 air is admitted ; and others, which are fully anaerobic, grow only when 

 free air or oxygen is shut off. Examples of these last are the bacillus 

 of symptomatic anthrax, of tetanus, and of the malignant oedema of 

 Koch. 



A large class of bacilli or bacteria are killed by dry air, by light, by 

 artificial heat, and by prolonged intense cold, but are capable, when 

 adverse influences act upon them, as by deficiency or inappropriate- 

 ness of the nutritive medium, of forming spores, minute germs which 

 are scattered abroad in a condition of far stronger defense, and capable 

 of resisting for some considerable time prolonged exposure to sun- 

 light and even to boiling water, to drying, to various antiseptic chem- 

 icals, and to any possible natural cold. The spore-bearing faculty 

 belongs to a variety of species of bacilli, both x>athogenic and harmless. 



1 "The atmosphere is the most universal medium or vehicle" of their poisons to 

 the breathing organs and intestines. (Professor Corfield. medical officer of St. 

 George's, Hanover Square, London.) 



