GENETICS: THE HERITABLE TRANSMISSION OF CATALYSTS 175 



ucts of its metabolism or through its own body, living or dead. 

 In general, each higher form of life depends upon simpler forms 

 to supply it with essential molecules, either for the main mass of 

 its food (fats, carbohydrates, proteins), or for many trace sub- 

 stances (e.g., vitamins, minerals), largely needed to make up the 

 catalytic machinery of the body, whereby the food molecules are 

 molded into its own species-specificity through the analytic and 

 synthetic action of its own catalysts. All this shows the truth of 

 the French aphorism: "Rien n'est la proie de la mort; tout est la 

 proie de la vie." (Nothing is the prey of death; everything is the 

 prey of life.) 



Apart from the obvious fact that the chemical nature of "food" 

 has thus an important evolutionary aspect, 21 we may refer to 

 symbiosis and parasitism, in which bionts live in very close asso- 

 ciation. Many parasites (e.g., tapeworms) pass part of their life 

 cycles in intermediate hosts. The wood-eating termite would 

 starve to death on this diet, were it not for the fact that it harbors 

 an intestinal messmate (an endameba) whose catalysts can convert 

 the wood into substances which the termite can utilize as food. 

 Cleveland found that slight increase in oxygen pressure kills the 

 endameba without harming the termite, but the termite then 

 starves to death on a diet of wood. 



Only recently (since about 1870) symbiosis was first discovered 

 in lichens, which consist of an association of a higher fungus with 

 a unicellular or filamentous alga. The fungus supplies water, 

 salts, nitrogenous substances and "lichen acids" which slowly at- 

 tack rocks, while the alga synthesizes carbohydrate; so that the 

 partnership can succeed where either member would fail. Not 

 only have lichens been "synthesized" from suitable fungus and 

 alga, but small lichen-thalli have been grown on nutritive solu- 

 tions in the absence of their algal constituent. The culture of 

 orchids from seed became possible only after it was found that in 

 nature a certain symbiotic fungus surrounds the seeds with special 

 moisture and other conditions. Similar is the case of trailing 

 arbutus, that delicate gem of the woodland in earliest spring. 



Since there seems to be an ever-increasing amount of experi- 

 mental evidence that some non-genic heritable changes actually 

 are transmitted, we are justified in asking this question: How can 

 heritable factors, apart from genie and chromosomal changes, 

 enter into and affect the germ cells (gametes) through which 

 heredity is transmitted? 



