. Bacteria in relation to soil fertility. Soil microbiology; Bacteriology, Agricultural. 2o8 BACTERIA AND SOIL FERTILITY time as they did in the absence of arsenic. The Paris green, however, is poisonous to this group of organisms in the minut- est quantities. This is due to the copper and not to the arsenic found in the compounds. How Does the Arsenic Act?—We may, therefore, conclude that arsenic stimulates all the beneficial bacteria. But how does it act? Will it stimulate for a short time and then allow the microorganism to drop back to its original or to a lower level as does alcohol and v
. Bacteria in relation to soil fertility. Soil microbiology; Bacteriology, Agricultural. 2o8 BACTERIA AND SOIL FERTILITY time as they did in the absence of arsenic. The Paris green, however, is poisonous to this group of organisms in the minut- est quantities. This is due to the copper and not to the arsenic found in the compounds. How Does the Arsenic Act?—We may, therefore, conclude that arsenic stimulates all the beneficial bacteria. But how does it act? Will it stimulate for a short time and then allow the microorganism to drop back to its original or to a lower level as does alcohol and various other stimulants when given to. Fig. 42.—Beans grown on arsenic treated soil. No. 41 received no arsenic the others small increasing quantities. Note the greater growth in 45 and 46 due to the arsenic. (After Stewart.) man? Or will it act as does caffeine—continue to stimulate? From the results on men and horses the former might be expected, for although the arsenic eaters of India and Hungary maintain that the eating of arsenic increases their endurance—and there is considerable evidence to indicate this—it is only for a short time. If the use be not continued the arsenic eaters cannot endure as much physical exertion as can others who are not addicted to the drug. Many European horse dealers place small quantities of arsenic in the daily corn of the horse for they find it improves its coat. If a horse, however, has been doped on arsenic for any length of time it seems necessary to continue the practice; other- wise, the animal rapidly loses his condition. Similar results might be expected with the bacteria, and ex- periments have shown that although during the first few weeks the bacterial activity of soils containing small quantities of ar-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original
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