Page:The Scientific Monthly vol. 3.djvu/307

 ORIGIN AND EVOLUTION OF LIFE 301

while we know it to be the physical basis of inheritance and the pre- siding genius of all phases of development, we can not form the slightest conception of the mode in which the chromatin speck controls the des- tinies of Sequoia gigantea and lays down all the laws of its being for a period of five thousand years.

We are equally ignorant as to how the chromatin responds to the actions^ reactions and interactions of the body cells, of the life environ- ment, and of the physical environment, so as to call forth a new adaptive character,-* unless it be through some catalytic agencies (p. 8). Yet in pursuing the history of the evolution of life upon the earth we may constantly keep before us our fundamental biologic law^^ that evolution lies within four complexes of energies, which are partly visible and partly invisible, namely :

1. The evolution of the physical environ- ment;

12. The individual development of the organism, namely, of its protoplasm controlled and directed by its chromatin ;

3. The heredity evolution of the chro-

matin with its constant addition of new powers and energies;

4. The evolution of the life environ-

ment, beginning with the protocel- lular chemical organisms and such intermediate organisms as bac- teria, and followed by such cellular and multicellular organisms as the higher plants and ajiimals.

CHLOROPHYLr. AND THE ENERGY OF SUNLIGHT

As bacteria seek their energy in the geosphere and hydrosphere, chlorophyll is the agent which connects life with the atmosphere, col- lecting the carbon from its union with oxygen in carbon dioxide. The utilization of the energy of sunlight in the capture of carbon from the atmosphere through the agency of chlorophyll marked the second great phase in the evolution of life, following the first bacterial phase. The chief energy elements, nitrogen and (less frequently) carbon, were cap- tured by bacteria through molecule-splitting in the presence of heat, but without the powerful aid of sunlight.

It is the fossilized tissue of plants which leads us to the conclusion that the agency of chlorophyll is also extremely ancient. Near the base of the Archean rocks^® graphites are obsen-ed in the Grenville series

^ Wilson, E. B., 1906, p. 434.

aTOsborn, H. F., 1912.

28Pir88on, Louis V., and Schuchert, Charles, 1915, p. 545.

��Incessant competition, selection, intra- Felection (Roux), and elimination between all parts of organisms in their chromatin energies, in their protoplasmic energieF, and in their actions, reactions and inter- actions with the living environ- ment and with the physical envi- ronment.

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