554 THE HISTORY OF BIOLOGY 



evolution of the individual it is possible to conclude that of the species. 

 The species is a summary of all similar individuals and, as such, an absolute 

 idea; similarly, there are many circles, ellipses, and other geometrical figures, 

 but their ideas are essentially different — and in the same way the species 

 have no intertransitional forms. "Die absolute Verschiedenbeit der Arten scheint 

 mir durch die Erjahrung hinldngliclj bestdtigt, und allgemein genug angenommen, 

 um auch ihrerseits die Absolut he it der Begrijfe ■zii bestdtigeti." And like the species 

 the higher systematical categories also possess their absoluteness; the vege- 

 table and the animal kingdoms have no transitions, for " dieser Annahme ivider- 

 spricht schon die Absolutheit der Begriffe. ' ' If this is not Hegelianism, it is at any 

 rate very near it. 



His micella theory 

 The ideas expounded in this work of his early years proved in many respects 

 to have a decisive influence on Nageli's future development. In his work on 

 starch granules he presents his once famous micella theory, which again 

 shows his tendency to transfer the deductions of geometry to biology. Ac- 

 cording to this theory the cells and their derivatives are composed of parti- 

 cles called "micellas," which are supposed to be composed of a number of 

 molecules, possess a regular crystalline form, and in a dry state keep close 

 to one another, owing to their mutual attraction; in certain circumstances, 

 however, the micellas attract water, which penetrates in between them and 

 surrounds each one of them, and through this action arises tissue. This the- 

 ory, which was irreconcilable with the findings of physics and consequently 

 had to be abandoned even during the lifetime of its originator, shows how 

 he strove to compare animate and inanimate matter; in actual fact he denies 

 any principial difference between them. In consequence he believed also in 

 spontaneous generation, stubbornly maintaining that doctrine throughout 

 his life; he certainly recognized Pasteur's experiments, but he considered that 

 they did not demonstrate the impossibility of spontaneous generation, and 

 to his mind spontaneous generation is ' ' nicht eine Frage der Erjahrung und des 

 Experiments, sondern eine aus dem GesetT^e der Erhaltung von Kraft und Stoff fol- 

 gende Tatsache." In his youth he believed in the spontaneous generation of 

 unicellular sponges and believed that it could be demonstrated by experi- 

 ment; when he did not succeed, he assumed the spontaneous generation of 

 very primitive unicellular creatures, and in his old age he continued his re- 

 treat, inasmuch as he assumed as products of spontaneous generation a kind 

 of extremely primitive life-units, whereof countless numbers go to form one 

 cell, and which he termed " probia." But he was undeniably more consistent 

 than Haeckel in not moving spontaneous generation back to the beginning 

 of the world, holding that it could just as well take place now as then, 

 "for the difficulty of letting a cell arise out of formless chemical substance 

 is not a jot greater for primeval times than for modern times." We must 



