256 Heredity and Eugenics 



and physical principles involved in the passage of fluids 

 from one part to another or to the outside, and something 

 of the role which katalytic changes play in organic activi- 

 ties. The time has not come when this information can be 

 directly applied to the problem of the chemical nature of 

 germinal changes. 



As regards form and pattern, the biologist is confronted 

 in organisms with the same difficulties as are presented to the 

 physicist and chemist to explain form and pattern in non- 

 living substances. No physicist would presume to say what 

 it is in the composition of a crystal which makes so definitely 

 for a specific form of face, hardness, and optical properties. 

 The problem is the same in both living and non-living 

 substance, and the forces which determine form and pattern 

 seem to be properties of the entire mass and are not local- 

 ized, and are probably produced in organisms, as in non- 

 living masses, by the sum total of the interactivities of 

 the mass at the moment of observation. 



In every part of the organism there is a symmetry which 

 is the outgrowth of the original symmetry from which the 

 organism developed. Variations in the secondary or later 

 symmetries may be large, but almost never are there 

 variations in the fundamental symmetries which distinguish 

 phyla. Evolution is mainly concerned in the problem of 

 the formation of species or attributes with variations in 

 these secondary symmetries and patterns. I have shown 

 how certain of these symmetries may be modified. 



Not the slightest clue of what it is that is modified in the 

 germ cells of a particular species as the result of any modi- 

 fying process has been recorded, and the usual attempted 

 explanations are based upon assumed a-priori conceptions, 

 usually atomistic in character, on the order of Darwin's 



