PROTOPLASM AND CHROMATIN 97 



of the chromatin; and the evolution of Hfe is essentially the 

 evolution of the chromatin energies. It is in the inconceivable 

 physicochemical complexity of the microscopic specks of 

 chromatin that life presents its most marked contrast to any 

 of the phenomena observed within the lifeless world. 



Although each organism has its specific constant in the 

 cubic content of its chromatin, the bulk of this content bears 

 little relation to the size of the individual. This is illustrated 

 by a comparison of the chromatin content of the cell-nucleus 

 of Trillium, a plant about sixteen inches high, with that of 

 Sequoia sempervircns, the giant redwood-tree of California, 

 which reaches a height of from 200 to 340 feet' and attains an 

 age of several thousand years (Fig. 14); we observe that the 

 chromatin bulk in Sequoia is apparently less than that in 

 Trillium. 



The chromatin content of such a nucleus is measured by 

 the bulk of the chromosome rods of which it is composed. In 

 the sea-urchin the size of the sperm-nucleus, the most compact 

 type of chromatin, has been estimated as about i /ioo,ooo,ooo 

 of a cubic millimetre, or 10 cubic microns, in bulk.- Within 

 such a chromatin bulk there is yet ample space for an incal- 

 culable number of minute particles of matter. According to the 

 figures given by Rutherford'^ in the first Hale Lecture the dia- 

 meter of the sphere of action of an atom is about i / 100,000,000 



^ Jepson, Willis Linn, 191 1, p. 23. - E. B. Wilson, letter of June 28, 1916. 



^ It is necessary, observes Rutherford, to be cautious in speaking of the diameter of 

 an atom, for it is not at all certain that the actual atomic structure is nearly so extensive 

 as the region through which the atomic forces are appreciable. The hydrogen atom is the 

 lightest known to science, and the average diameter of an atom is about 1/100,000,000 

 of a centimetre; but the negatively charged particles known as electrons are about 1/1800 

 of the mass of the hydrogen atom. . . . These particles travel with enormous velocities 

 of from 10,000 to 100,000 miles a second. . . . The alpha particles produce from the 

 neutral molecules a large number of negatively charged particles called ions. The ioniza- 

 tion due to these alpha particles is measurable. ... In the phosphorescence of an 

 emanation of pure radium the atoms throw off the alpha particles with velocities of 

 10,000 miles a second, and each second five billion alpha particles are projected. — Ruth- 

 erford, Sir Ernest, 1915, pp. 113, 128. 



