INTRODUCTORY DISCUSSIONS 147 



originate from a starting-point which exhibits less visible 

 inanifoldness than does the end ; crystals are always 

 themselves, and might almost be said to show nothing but 

 mere increase of size. A third difference might be found 

 in the fact that crystals during their growth use the 

 specificity of their medium in its very specificity, whilst to 

 organisms the medium is only a means of growth, their 

 specificity resting in themselves ; but I shall not lay much 

 stress upon this point in our present analysis. 



It may be objected to the second of our definitions that 

 researches of the last few years, especially those of Eauber 

 and Przibram, 1 have shown a very high faculty of restitution 

 in crystals. Broken crystals, in fact, are not only capable 

 of restoring the parts that are wanting, a process resembling 

 regeneration, but are also able in some cases to transform 

 themselves into a new and smaller whole, by changing all 

 their proportions a process which resembles the differen- 

 tiation of an harmonious-equipotential system. How could 

 I say in the face of such facts that crystals are always 

 themselves, and show nothing but mere growth ? I could 

 say so, because in spite of their so-called " restitution/' 

 crystals go through their formative processes only with the aid 

 of the forces which also determine their growth, and with no 

 other help whatever. These forces show different intensities 

 in the different directions of space, embracing a typical 

 arrangement of the relative maxima of these intensities, and 

 this character of their formative forces, taken together with 

 some relations of tension between the solid material of the 

 crystal and the solution surrounding it, is sufficient to 



1 Arch. f. Entw.-mech. 22, 1906. The full literature will be found 

 there. 



