38 HAECKEL 



and was the reality of the plant-world in a state of 

 flux like the sea ? Teachers and books insisted 

 that the " species " is, in its absolute nature, the 

 basis of all botanical science, the great and sacred 

 foundation that the Moses of botany and zoology^ 

 Linne, had laid down for ever. How could it 

 be so ? 



The mature worker would look back on this 

 dilemma of his youth with a smile of satisfaction 

 thirty years afterwards. He would know then 

 what sort of a nut it was that he was trying to 

 crack in his early speculations. It was nothing 

 less than the magnificent problem that presented 

 itself to Darwin, the crucial question of the fixity 

 or variability of species. *' The problem of the 

 constancy or transmutation of species," he wrote, 

 ''arrested me with a lively interest when, twenty 

 years ago, as a boy of twelve years, I made a 

 resolute but fruitless effort to determine and dis- 

 tinguish the ' good and bad species ' of black- 

 berries, willows, roses, and thistles. I look back 

 now with fond satisfaction on the concern and 

 painful scepticism that stirred my youthful spirits 

 as I wavered and hesitated (in the manner of most 

 ' good classifiers,' as we called them) whether to 

 admit only ' good ' specimens into my herbarium 

 and reject the 'bad,' or to embrace the latter and 

 form a complete chain of transitional forms be- 

 tween the * good species ' that would make an end 

 of all their 'goodness.' I got out of the difficulty 

 at the time by a compromise that I can recommend 

 to all classifiers. I made two collections. One, 



