666 POPULAR SCIENCE MONTHLY. 



that they have common ancestors, that they have developed 

 through the ages until now. 



Another field of botanical study is being cultivated by those 

 who devote themselves to the investigation of the adaptations of 

 plants to their surroundings. The adaptations are so many and 

 so perfect that all are tempted (and many yield) to let their senti- 

 mental imaginations replace that spirit of critical inquiry without 

 which no scientific work of lasting value can be done. The adap- 

 tations for disseminating seed the winged fruits of our maples, 

 elms, and lindens, for example, or the silken parachutes of the 

 dandelion and the milkweed, the explosive touch-me-not, and the 

 wild crane's-bill with its boomerang show one how a region 

 devastated by glaciers, fires, or floods can be repopulated. The 

 relations of flowers to the insects which are to pollenate them were 

 first discovered by Christian Conrad Sprengel, and described in a 

 now rare and highly prized book, The Secret of Nature Revealed ; 

 but botanists left Sprengel and his secret to themselves. Darwin 

 rediscovered the secret, then discovered the book, and since then 

 the world has been deluged with writings good and bad on this 

 most fascinating subject. The whole field of phytobiology, the 

 adaptations of plants to their surroundings, is open to every one 

 whose interest in Nature takes him into the fields and woods 

 even into the public parks. No knowledge of technical terms is 

 necessary to enable one to pull apart one of the great horse-chest- 

 nut buds, to notice the water-proofing varnish on the outside, the 

 scale armor just within, the soft, downy padding which protects 

 the minute leaves and the tip of the stem from sudden changes of 

 temperature, to see that leaves or flower cluster are already formed 

 in miniature ready to burst their coverings when the favorable 

 time shall come. 



The minute internal structure of the plant is as important a 

 subject for investigation as the more evident features of which I 

 have just spoken. The microscopic study of plants leads one to 

 the most fundamental questions in biological science. It was in 

 consequence of the microscopic studies of a botanist that it was 

 discovered that all organisms are composed of cells, that these 

 cells are essentially minute masses of a viscid substance proto- 

 plasm which is " the physical basis of life." Is it any wonder, 

 then, that men have devoted their lives to its study, seeking 

 through a knowledge of its structure to learn something of the 

 life of which it is the physical, tangible embodiment ? 



Among plants as among animals there are two modes of repro- 

 duction, the sexual and the nonsexual. Higher animals repro- 

 duce themselves only sexually. Some of the higher plants re- 

 produce themselves in the wild state nonsexually as well as 

 sexually, as, for example, the blackberry by its runners, the pop- 



