Page:The Scientific Monthly vol. 3.djvu/296

 290 THE SCIENTIFIC MONTHLY

ferred in certain diseases. The chemical constitution of these micro- scopic and ultra-microscopic forms is doubtless highly complex.

In their power of finding energy or food in a lifeless world the bac- teria known as prototrophic or "primitive feeders" are not only the simplest known organisms, but it is probable that they represent the sur- vival of a primordial stage of life chemistry. These bacteria derive both their energy and their nutrition directly from inorganic chemical compounds : such types w^re thus capable of living and flourishing on the lifeless earth even before the advent of continuous sunshine and long before the first chlorophyllic stage (Algae) of Hie evolution of plant life. Among such bacteria possibly surviving from Archeozoic time is one of these "primitive feeders/' namely, the Nitroso monas of Europe.^ For combustion it takes in oxygen directly through the in- termediate action of iron, phosphorus, or manganese, each of the single cells ])eing a powerful little chemical lalwratory which contains oxidiz- ing catalyzers, the activity of which is accelerated by the presence of iron and of manganese. Still in the primordial stage Nitroso monas lives on ammonium sulphate, taking its energy (food) from the nitro- gen of ammonium and forming nitrites. Living with it is the symbiotic bacterium Nitrohacfer, which takes its energy (food) from the nitrites formed by Nitroso mona^, oxidizing them into nitrates. Thus the.^e two species illustrate in its simplest form our law of the interaction of an organism (Niirohacter) with its life environment {Nitroso monas) *

The discovery of the chemical life of these bacteria marks an ad- vance toward the vsolution of the problem of the origin of life as impor- tant as that attending the long prior discovery of chlorophyll. The prototrophic forms above noted are classed among the nitrifying bac- teria: they take up the nitrogen of ammonia compounds and oxidize them first into nitrites and then into nitrates. Heraeus and Hiippe (1887) were the first to observe these forms in action in the soils and to prove that pre-chlorophyllic organisms were capable of development, with ammonium and carlx)n dioxide as their only sources of energy. Eight chemical "life elements^' are involved in this process, namely, potassium, phosphorus, magnesium, sulphur, calcium, chlorine, nitro- gen, and carbon. This discovery was confirmed by Winogradsky (1890, 1895), who showed that two symbiotic groups existed; one the nitrUe formers, Nitroso monas, and the other the nitrate formers, Nitrobacter. These bacteria are not only in(lo})ondent of life compounds, but even small traces of organic carbon and nitrogen compounds are injurious to them. Later Xathanson (1902) and Beyjerinck (1904) showed that certain sulphur bacteria possess similar powers of converting ferrous to ferric oxide, and II2S to SOo. These organisms are widespread:

3 Fischer, Alfred, 1900, pp. 51, 104.
 * Jordan, Edwin O., 1908, pp. 492-497.

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