456 TROPICAL NATURE 



of comparing the productions of one country with those of 

 another ; of investigating the physical and biological relations 

 of islands and continents; of watching the struggle for 

 existence in regions where civilisation has not disturbed the 

 free action and reaction of the various groups of animals and 

 plants on each other ; and, what is perhaps more important 

 still, the ample leisure to ponder again and again on every 

 phase of the phenomena which presented themselves, free 

 from the attractions of society and the disturbing excitement 

 of daily association with contemporary men of science, 

 these are the conditions most favourable to the formation of 

 habits of original thought, and the months and years which 

 at first sight appear intellectually wasted in the companion- 

 ship of uncivilised man, or in the solitary contemplation of 

 nature, are those in which the seed was sown which was 

 destined to produce in after years the mature fruit of great 

 philosophical conceptions. Let us then first glance over the 

 Journal of Researches, in which are recorded the main facts 

 and observations which struck the young traveller, and see 

 how far we can detect here the germs of those ideas and 

 problems to the working out of which he devoted a long and 

 laborious life. 



The Journal of Researches 



The question of the causes which have produced the dis- 

 tribution and the dispersal of organisms seems to have been 

 a constant subject of observation and meditation. At an 

 early period of the voyage he collected infusorial dust which 

 fell on the ship when at sea, and he notes the suggestive fact 

 that in similar dust collected on a vessel 300 miles from land 

 he found particles of stone above the thousandth of an inch 

 square, and remarks : " After this fact, one need not be sur- 

 prised at the diffusion of the far lighter and smaller sporules 

 of cryptogamic plants." He records many cases of insects 

 occurring far out at sea, on one occasion when the nearest 

 land was 370 miles distant. He paid special attention to the 

 insects and plants inhabiting the Keeling or Cocos, and other 

 recently formed coralline or volcanic islands ; the contrast of 

 these with the peculiar productions of the Galapagos evidently 

 impressed him profoundly ; while the remarkable facts pre- 



