424 THE POPULAR SCIENCE MONTHLY. 



Now, a number of careful investigations have been made of the 

 constituents of miasmatic marshes in various parts of the world, with 

 the following results : They contain from thirty to thirty-five per 

 cent, of vegetable organic matter. This consists of humic, ulmic, 

 cremic, and apocremic acids, all substances requiring renewed chemical 

 investigation. Various minute vegetable algoid forms are revealed 

 by microscopic examination bacteria, vibriones, and microzymes. But 

 all these so-called impurities are found in nearly every running stream 

 and in many harmless well-waters, and to condemn water on account 

 of their presence would be really to reject all waters, even rain, in 

 which minute algoid vesicles (protococci) are often found. Even 

 distilled water may contain bacteria and vibriones. Although, there- 

 fore, admitting that water may be contaminated by the presence of 

 malaria, it by no means follows that this poisonous ingredient has any 

 relation to the organic impurities mentioned, or that the latter are in 

 any way injurious, but we should none the less be cautious as to the 

 source of our drinking-water. 



The stratum of air overlying typical malarial marshes has also 

 been examined with particular care. It has been found to contain an 

 excess of carbonic acid watery vapor in large quantity often car- 

 buretted hydrogen, and occasionally free hydrogen, ammonia, and 

 phosphuretted hydrogen. If the marsh contains sulphates, sulphu- 

 retted hydrogen, is present. Its organic matter blackens sulphuric 

 acid gives a reddish color to nitrate of silver has a fiocculent 

 appearance, a peculiar odor, and affords evidence of ammonia. The 

 amount in Becchi's analysis was .000118 grain in each cubic foot 

 of air. Ozone had no effect upon it. Besides this organic material, 

 various vegetable and animal matters are arrested when the marsh-air 

 is drawn through water or sulphuric acid debris of plants, infusoria, 

 insects, and even small Crustacea. Dr. Balestra has described spores 

 and sporangia of a little algoid plant in the air of the Pontine Marshes. 

 Lemaire and Gratiolet, in 1864, found in the air of one of the most 

 unhealthy marshes of Sologne spherical, ovoid, and fusiform spores and 

 a large number of pale cells, products, no doubt, of vegetable putrefac- 

 tion. It has been supposed, by Schonbein and others, that ozone is 

 deficient in marsh-air ; that the quantity of ozone in the atmosphere 

 and the prevalence of malarial diseases have an inverse proportion ; 

 and that ozone, by virtue of its supposed power of destroying organic 

 matters in the air, is an antidote to miasm. There is, however, no 

 evidence at all that ozone and malaria are antagonistic, or bear to 

 each other any relation whatever. These various examinations, though 

 interesting, bring us no nearer to a solution of the question, What is 

 the nature of malaria? All of the many substances and forms thus 

 far observed in malarial localities may be found equally in districts 

 perfectly salubrious. 



That it gains access to the system principally through the respira- 



