88 UNIVERSAL EVOLUTION 



evolution, and defends very ably the theory of natural 

 selection. He applies the selection theory to the deter- 

 minants located in the ids of the germ plasm. An id 

 is the bearer of the hereditary qualities. Thousands 

 of the determinants go to the make-up of an id. They 

 are so small that they are invisible under a microscope, 

 but they feed, grow, and multiply by division. These 

 determinants control the parts of the developing em- 

 bryo. They differ among themselves. Those of a 

 nerve cell differ from those of a muscle. These tiny 

 determinants are made up of yet smaller units, called 

 biophers, or bearers of life. These determinants vary 

 in growth, and give rise to corresponding variations in 

 the organs, cells, or cell group, of the organisms, into 

 which they develop. They ceaselessly fluctuate in size 

 and quality, because of their unequal nutrition. Like 

 blades of grass in a meadow, they vary in accordance 

 with the different amounts of nutriment carried to 

 them. Weissman says, " If a determinant ; for instance, 

 of a sensory cell receives for a considerable time, more 

 abundant nutrition, than before, it will grow more 

 rapidly become bigger and divide more quickly; and 

 later, when the id concerned develops into an embryo, 

 this sensory cell will become stronger, than in the 

 parents." This is the way he accounts for variations 

 in organisms. 



If this theory is correct, then there is a natural 

 selection going on in the ids, determinants, and bio- 

 phers, by which the fittest to produce the most vigorous 

 organisms do the work, produce the variations, and 

 when the new forms are born, then the same principle 

 of natural selection works in preserving some and 

 annihilating others. This is a very fascinating and 

 plausible theory. But it is too speculative to be ap- 



