TaM DISPERSION OF SHEDS ;J41 



relative structures, and that it merely so happens 

 that they serve a special but incidental purpose 

 in disseminating the plant. If we once assume 

 that every feature of a plant is adapted to some 

 specific purpose, and that it has arisen by means 

 of the effort of the plant to adapt itself to such 

 purpose, we are apt to find adaptations where there 

 are none. We are really throwing our own 

 thoughts and feelings into the phenomena; and we 

 are developing a superficial method of looking at 

 nature. (Compare 338, 339.) 



423a. The word adaptation is used technically, in evolution writ- 

 ings, to designate the fitness of an organism, or any part of an or- 

 ganism, to perform certain functions or to live in certain environ- 

 ments. Thus, a flower is adapted to cross-pollination, or a plant 

 to dry soil, or to a cold climate. Adaptive modifications are such 

 as obviously prepare the organism to live in given environments. 

 ^ 4236. Correlative or correlated characters are concomitants of 

 the main or type characters. They are incidental features, which 

 have been carried along by the main line of ascent, and which 

 are of little significance to the present well-being of the organism. 



423c. The genealogy of an organism is called its phylogeny. 

 The life-history of a single or individual organism is its ontogeny. 

 That is, phylogeny is the natural history of the race, whereas 

 ontogeny is the natural history of a single individual. Phylogenetic 

 characters, therefore, are those which have come down from the 

 ancestry ; ontogenetic characters are those whic{f have originated 

 within the life-time of a given individual. 



i2Zd. An acquired character is an ontogenetic character which 

 is obviously the result of some environmental circumstance, as of 

 soil, light, or temperature. 



Suggestion. — Let the teacher assign one kind of plant to each 

 pupil, asking him to discover how the seeds are dispersed. 



