182 HAECKEL 



somewhat later. His exhaustive Monograph on 

 the Monera was not published until 1868. Man's 

 genealogical tree was privately circulated at Jena 

 in two essays in October and November 1865. 

 They were published in the Virchow-Holtzendorff 

 collection in 1868 (" The Origin and Genealogical 

 Tree of the Human Kace"). But in both cases 

 the substance of the work, as an accumulation 

 of facts, is much older. And this work was, of 

 course, only possible in connection with a number 

 of further conclusions : in regard to spontaneous 

 generation, life and death, the crystal and the 

 cell, the mathematical form of organisms, the 

 nature and limits of individuality, the method of 

 research, the new natural philosophy, God, and 

 so on. 



It was an enormous programme, with a Para- 

 disaic freshness. Everything was new and great ; 

 and all came from one brain. There was only 

 one man with whom he discussed his ideas as 

 they formed, Carl Gegenbaur, who has undoubtedly 

 had a great, if unconscious, influence on them. 

 Haeckel's grateful recognition of Gegenbaur's help 

 in later years was endless and touching. " Thou 

 it was," he writes to him a little later, " that led 

 me to begin my academic teaching at our beloved 

 Jena six years ago, at the Thuringian university 

 in the heart of Germany, that has, like a beating 

 heart, sent out its living waves of freedom and 

 alertness of mind over Germany for three hundred 

 years. At this nursery of German philosophy and 

 science, under the protection of a free State whose 



