34 LIFE: ITS ORIGIN AND NATURE 
each of which is thought to contain a complete 
inheritance. Each id consists of numerous 
primary constituents or “determinants.” A 
determinant is usually a group of so-called 
“biophors,”—the minutest vital units known to 
us. The biophor in turn is an integrate of nu¬ 
merous chemical molecules. 
It will thus be seen that the mechanism of 
heredity is an exceedingly complex phenomenon 
which is only what we should expect, in view of 
the complexity of life itself. The great puzzle 
is how all the potentialities of a living being 
can be crowded into the microscopic particles 
which form the physical basis of heredity. The 
character of the offspring depends (as J. 
Arthur Thompson points out, in his work on 
“Heredity”), upon the adjustments arrived at 
among the different sets of determinants of 
paternal and maternal origin. 
There are those, however, who refuse to see, 
in these microscopic units more than the 
physical counterparts of life itself. It has been 
contended that life is something over and above 
matter, and that heredity is really carried in 
some super-physical realm, (a sort of “astral” 
heredity), and that the physical bearers of 
heredity known to us represent, merely, the 
physical vehicles for this life-energy—in much 
the same way that the human brain is the 
material instrument of thought and conscious¬ 
ness Whether such a view of the case appears 
plausible will depend, of course, upon the view 
we take of the universe. If any super-physical 
realm be admitted, such a view is actually neces¬ 
sitated, while from the purely mechanistic 
