360 MY LIFE 



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 eluci- 

 dation. My paper written at Sarawak rendered it certain 

 to my mind that the change had taken place by natural suc- 

 cession 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 allies by 

 slight yet perfectly definite and constant characters. One 

 would expect that if it was a law of nature that species were 



