GERMINAL VARIATIONS AND EVOLUTIONS 573 



the offspring various adjustments must be made. Some deter- 

 minants will be able to assert themselves while others will remain 

 latent, and as a result of the adjustments in the germ-plasm 

 variations may appear in the characters of the offspring. Also 

 two newly associated determinants may so work together as to 

 cause a variation to arise in the characters of the offspring not 

 present in either parent. For example, two white flowered 

 plants sometimes produce red flowered offspring when crossed. 



Variations among determinants may be due to physiological 

 disturbances. The determinants are in competition with each 

 other for food and water, and there may occur such a variation 

 in the distribution of food and water as to cause a variation in the 

 nourishment of the different determinants. As a result deter- 

 minants previously poorly nourished and inactive get a monopoly 

 on the food supply and become active, while others previously 

 active become inactive due to loss of nourishment, thus causing 

 variations in the structure and function of offspring to arise not 

 previously present and others previously present to disappear. 

 The determinant that suddenly becomes active may be one for a 

 certain flower color, for hairy epidermis, for thick stalk, or for any 

 other character. 



The variations among the determinants may be induced by the 

 environment. Since the germ-plasm is fed and protected by the 

 body or somatoplasm of the individual, changes, such as drought, 

 shade, intense light, lack of food, etc., indirectly affect the germ- 

 plasm at the same time they directly affect the somatoplasm. 

 Due to the indirect effects of the environment, certain deter- 

 minants previously inactive may become active, and others 

 previously active may become inactive. Thus drought may 

 cause such a shift among the determinants that the color of the 

 flower, length of ear, height of plant, or any other character is 

 changed. 



The chief idea in this theory is that all hereditary variations 

 first originate as variations among the determinants of the germ- 

 plasm. All variations that involve only the somatoplasm, as most 

 fluctuating variations do, are not hereditary. Hereditary 

 variations first appear among the determinants of the germ-plasm 

 and later manifest themselves as variations in the body characters 

 of the individual. Hereditary variations come from within and 

 not from without. 



