320 O. F. COOK 



mechanical " forces" hitherto recognized, only shows in higher 

 relief their hyperphysical stability. 



The atomic theory of matter has led Professor DeVries and 

 others to assume that morphological alterations are " incumbent 

 on slight chemical changes of the representative particles of 

 the hereditary qualities." ^ We know, however, that organic 

 structures and vital processes persist through a wide range of 

 physical conditions, and in spite of changes of the material 

 particles, or even of the chemical substances of which the living 

 tissues are composed. There is a stability of motion as well as 

 of rest ; new characters can be preserved by prepotency better 

 than by segregation. 



The higher we go in the scale of organic existence the more 

 obvious these facts become. To keep alive the bodies of the 

 higher animals there must be a constant supply of new ma- 

 terials, and a removal of the fatigue-products of the high-grade 

 vital activity. The animals were able to out-strip the plants 

 largely because they developed superior facilities for secretion 

 and excretion. They are able to make use of a much greater 

 variety and complexity of compounds and can also rid them- 

 selves of waste products with more freedom. Plants are able, 

 for the most part, to excrete only gaseous compounds ; other 

 rejectamenta have to be accommodated inside the cells or laid 

 down in the cell walls. 



The idea that the cellular bodies of plants and animals are 

 built up on simple principles of "developmental mechanics" 

 sees no significance in the wonderful series of gradually super- 

 posed complexities which have attended the advance of organ- 

 isms to their present stages of perfection. To build up our 

 bodies, cells have become associated in immense numbers and 

 highly specialized inform, structure and function. The number 

 and complexity of chemical substances has likewise increased 

 from the simple inorganic compounds used by the soil bacteria 

 to those supplied by the mixed diet of civilized man. 



* Professor DeVries also explains in a preceding paragraph: "Chemical 

 substances are changed into others bv definite and measurable steps, and hence 

 it seems to me that this rule might prevail for the minutest material particles 

 which determine the hereditary qualities of organisms." (Harper's Magazine, 

 no : 210, January, 1905.) 



