256 Form and Color in Nature. 



for the purpose of keeping up family intercourse between 

 near relatives or friends. 



I have said but little of the development of organic form 

 excepting incidentally. To do even scant justice to this 

 side of the subject one should have at least an evening. 

 But Mr. Kimball's lecture to which I have referred you 

 treats one part of this question, and, beyond what I have 

 already said, I can only call your attention generally to a 

 few points. 



Upon the earth there are four fields in which organic 

 functions may be exercised in the liquids, in the solids, on 

 the surface of the earth, and in the air. Organic life seems 

 to have originated in the liquids, where, in the beginning, 

 substances having the same specific gravity were borne 

 about freely by mechanical causes, and thus brought into 

 contact with the ingredients which they required for nour- 

 ishment. What has been already said, coupled with the ex- 

 ercise of a little imagination, will lead you to see the natural 

 sequences of modification in this earliest medium, under 

 the influence of natural selection. The manner of produc- 

 tion of organs for locomotion and for grasping prey as well 

 as for perceiving it, together with the simultaneous special- 

 ization of function in the internal organization, do not call 

 for any unusual exercise of the powers of comprehension so 

 far as we can comprehend them at all. Nor does it seem 

 difficult to trace the steps by which some forms were in- 

 duced to attach themselves to the rocks and so live a sta- 

 tionary life, and by which others living close to the shore, 

 and from time to time left bare by the tide or the drying 

 up of shallow waters, should have become accustomed to a 

 terrestrial life. That some should remain amphibious, and 

 that some, both animal and vegetable, wandering inland, 

 should become wholly acclimated there, being modified to 

 conform to altered circumstances, we can realize. Bearing 

 in mind the extreme minuteness of the individual changes, 

 and the enormous period of time during which they have 

 occurred, there seems little required of our imagination ex- 

 cepting that which is in tolerably close accord with our 

 ordinary experience. Even when we contrast the worms and 

 other inhabitants of the soil, or of living or dead organic 

 matter with mammalia, both terrestrial and aerial such as 

 the bats, flying squirrels, and lemurs, or the reptiles and 

 their glorified descendants the birds, or the insects we are 

 no longer greatly troubled by their differences. 



