316 ECOLOGY 



Ecological matters are then worthy of the attention of the student of 

 morphology, heredity, and evolution. 



What is the significance in the fact that the white tiger-beetle 

 (Cicindela lepida) belongs to the first association in the development 

 of a forest community on sand, which we may say corresponds to a 

 family, and to the subterranean ground stratum (corresponding to genus) 

 and to the white tiger-beetle mores? Furthermore, that Cicindela 

 lecontei and the green tiger-beetle {Cicindela sexguttata) belong respec- 

 tively to different and older situations or associations ? We note that the 

 habitats in which the species occur are characterized by distinctly differ- 

 ent soils, moisture, amounts of shade and light. We note, furthermore, 

 that these animals are possessed of unusual powers of flight and 

 are able to select conditions suited to their physiological constitution. 

 Their mores characters are definite characters, which can be measured 

 in terms of reactions to measured complexes of physical and other 

 environmental factors. They are as clearly defined as any morphological 

 taxonomic characters and can be measured with the accuracy of any 

 physical phenomena. 



Doubtless to the student of genetics or evolution, the question of 

 the origin of such characters and their fixation in heredity is a leading 

 question. At this point we know little or nothing. Since nearly all 

 species have definite habitat preferences and since many varieties differ 

 slightly from the related species form in the matter of habitat preference, 

 it is probable that origin of a slight change in habitat preference, mean- 

 ing a slight change in reaction to physical factors, a change in ecological 

 optimum, is usually an early correlative of the origin of new races. 

 Still the so-called taxonomic characters may remain apparently 

 unchanged, while marked changes in habitat preference and in reaction 

 to physical factors are being brought about in plastic animals (56). 

 On the other hand, the segregation in the pure lines and races accom- 

 plished in experimental breeding often appears to take place without 

 any regard to environment (204). These two facts, accepted as they 

 stand, are in full accord and we might conclude that there are no rela- 

 tions between primary ecological characters and taxonomic characters. 

 Such, however, can hardly be strictly true, but we cannot see what the 

 real relations may be. If our point of view is correct the ecological 

 characters of a race experimentally segregated, or experimentally pro- 

 duced, must in practice consist primarily of reaction to physical factors 

 or combinations of physical factors or to entire environmental complexes; 

 secondly of a definite rate of metabolism, time of appearance or the like; 



