36o MY LIFE [Chap. 



description, and if neither Darwin nor myself had hit upon 

 "Natural Selection," I might have spent the best years of my 

 life in this comparatively profitless work. But the new ideas 

 swept all this away. I have for the most part left others to 

 describe my discoveries, and have devoted myself to the 

 great generalizations which the laborious work of species- 

 describers had rendered possible. In this letter to Bates I 

 enclosed a memorandum of my estimate of the number of 

 distinct species of insects I had collected up to the time of 

 writing — three years and a half, nearly one year of which had 

 been lost in journeys, illnesses, and various delays. The 

 totals were as follows : — 



Butterflies 



620 species 



Moths 



2000 „ 



Beetles 



3700 „ 



Bees, wasps, etc 



750 „ 



Flies 



660 „ 



Bugs, cicadas, etc 



500 „ 



Locusts, etc. 



160 „ 



Dragonflies, etc 



no „ 



Earwigs, etc. 



40 „ 



Total 



8540 species of Insects. 



It was while waiting at Ternate in order to get ready for 

 my next journey, and to decide where I should go, that the 

 idea already referred to occurred to me. It has been shown 

 how, for the preceding eight or nine years, the great problem 

 of the origin of species had been continually pondered over, 

 and how my varied observations and study had been made 

 use of to lay the foundation for its full discussion and 

 elucidation. My paper written at Sarawak rendered it 

 certain to my mind that the change had taken place by 

 natural succession and descent — one species becoming changed 

 either slowly or rapidly into another. But the exact process 

 of the change and the causes which led to it were absolutely 

 unknown and appeared almost inconceivable. The great 

 difficulty was to understand how, if one species was gradually 

 changed into another, there continued to be so many quite 

 distinct species, so many which differed from their nearest 



