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THE AMERICAN NATURALIST [Vol. L 



to adapt themselves to these conditions, and became sec- 

 ondarily facultative or obligate aerobes. Amoeboplasm, 

 on the other hand, can not exist without a supply of oxy- 

 gen. (2) My ooplasm can support temperatures of 90° C. 

 or even higher ; amoeboplasm can not support a tempera- 

 ture higher than 45° C. or 50° C. (3) Mycoplasm is 

 capable of building up albumins and complex organic 

 substances from inorganic materials ; amoeboplasm is in- 

 capable of doing so, but requires organic food. (4) My- 

 coplasm has restricted powers of locomotion and is in- 

 capable of amoeboid movement, or of forming the con- 

 tractile vacuoles seen commonly in amoeboplasm. (5) 

 Mycoplasm, in contrast to amoeboplasm, is rich in phos- 

 phorus and nuclein. (6) Mycoplasm is extraordinarily 

 resistant to poisons and utilizes as food many substances 

 that are extremely deadly to amoeboplasm, such as prussic 

 acid, strychnine and morphia. (7) Amongst minor dif- 

 ferences, mycoplasm is characterized by the presence of 

 iron in the combined state and possesses a far more com- 

 plicated structure than amoeboplasm, a peculiarity which 

 enables mycoplasmic cell-elements (chromosomes) to 

 function as the bearers of hereditary qualities. 



The course of the evolution of living beings, according 

 to Mereschkowsky, was as follows. The earliest forms of 

 life were "Biococci," minute ultra-microscopic particles 

 of mycoplasm, without organization, capable of existing 

 at temperatures near boiling-point and in the absence of 

 oxygen, possessing the power of building up proteins and 

 carbohydrates from inorganic materials, and very resist- 

 ant to strong mineral salts and acids and to various 

 poisons. From the Biococci arose in the first place the 

 Bacteria, which for a time were the only living inhabitants 

 of the earth. Later, when the temperature of the ter- 

 restrial waters had been lowered below 50° C, and con- 

 tained abundant organic food in the shape of Bacteria, 

 amoeboplasm made its appearance in small masses as non- 

 nucleated Monera which crept in an amoeboid manner on 

 the floor of the ocean and devoured Bacteria. 



