386 THE STUDY OF ANIMAL LIFE CHAP. 



Because of the correlation that exists in the living body 



^j */ 



there seems to be, as Bohn points out, a tendency for the 

 myogenic metabolism to spread, and the heart-muscle is 

 also strengthened. It is possible that although the germ- 

 cells are unaffected by the strengthening of any particular 

 muscle, they might in the course of time be affected by 

 a persistent exaggeration of myogenic metabolism in the 

 body. This suggests at least an interesting inquiry. 



Changes in function that have deeply saturating 

 influences on the individual body may have indirect 

 effects on the germ-cells and thus influence the next 

 generation. But this is a very different matter from 

 the transmission of a particular functional modification. 

 It must also be clearly understood that improvements 

 or disturbances in the function of a mammalian mother 

 with young often have a general strengthening or weaken- 

 ing effect on the offspring. 



2. The Influence of Surroundings. In ancient times 

 men saw the threads of their life passing through the 

 hands of three sister Fates of one who held the distaff, 

 of another who offered flowers, and of a third who bore 

 the abhorred shears of death. In Norseland the young 

 child was visited by three sister Norns, who brought 

 characteristic gifts of past, present, and future, which 

 ruled the life as surely as did the hands of the three 

 Fates. So, too, in days of scientific illumination, we 

 speak of life as determined by the organism's legacy or 

 inheritance, by force of habit or function, and by the 

 influences of external conditions or environment. What 

 the living organism is to begin with, what it does or does 

 not in the course of its life, and what surrounding influ- 

 ences play upon it, these are the three Fates, the three 

 Norns, the three Factors of Life. Organism, function, 

 and environment are the sides of the biological prism. 

 Thus we try to analyse the light of life. But inheritance 

 in its widest sense is only another name for the organism 

 itself, and function is simply the organism's activity. 

 The organism is real ; the environment is real, in it we live 

 and move ; function consists of action and reaction 

 between these two realities. 



