ADAPTATION 203 



ing must be selective and preserve both those 

 ontogenetically and those innately adapted. The 

 attack being on the mass of species and individ- 

 uals, it tends to preserve those that are alike/ 



G, Functional, Adaptations. The whales 

 living like sharks look like them. O shorn re- 

 marks : " If a primate begins to imitate the hab- 

 its of an ungulate by becoming herbivorous, it 

 also begins to acquire the dental cusps of an un- 

 gulate in about the same order as these cusps 

 would arise in an ungulate." 



I could paraphrase Osborn's words for the 

 Characins many times. The Characins have 

 taken on the habits of many fishes and have par- 

 alleled them while they diverged from each other. 

 A certain habit and habitat in fishes carries with 

 it a certain regulative adaptation. Living as a 

 sand-darter does, carries with it a sand-darter 

 shape. The question that confronts us first is 

 not, why does the sand-darter habit carry with it 

 a certain form, but what caused Characins to 

 adopt the darter habit? 



What caused Osborn's primate to begin to imi- 

 tate the habits of an ungulate? What caused 

 different Characins to begin to eat mud, crusta- 

 ceans, plants, plankton, and each other? 



Overproduction of individuals leading to 

 crowding, the struggle with the biological envi- 

 ronment for food (or light in the case of plants) , 



' No more striking example is found than in the old but uniform 

 deciduous habit of plants of the temperate region. 



