52 THE UNIVERSITY OF OKLAHOMA 



tween the various organs of an animal's body and between different 

 animals. Along with these two lines of biological research went in- 

 vestigations in embryology, paleontology, geological and geograph- 

 ical distribution, the whole culminating in the last half of the nine- 

 teen century in the doctrine of evolution. The last quarter of the 

 nineteenth century saw the most phenomenal advances in 

 microscopic investigations particularly in the early phases of embry- 

 ology, and in the structure and behavior of the animal and the 

 plant cell. All of these researches however had a morphological 

 background and a morphological point of view. In saying that 

 Systematic Zoology, Economic Zoology, Morphology, Embryology, 

 etc., were the main researches of the last century, we do not by any 

 means imp'y that they are no longer the subject of investigation. 

 As a m.atter of fact the actual output in each of these branches is 

 doubtless greater in volume than at any time in the past. But 

 the attack of these problems is not now purely a morohological one 

 and the main interest of today is in problems of different charac- 

 ter. The main current may move steadily forward in a certain 

 direction but a broad stream touches much that is outside the 

 main current. 



Thus far we have shown what the main objectives of the 

 present in zoological research are not. It may be added that 

 the evolution doctrine as it is commonly understood, that is, the 

 study of its evidences and factors, is not one of the main objectives. 

 So far as professional biologists are concerned the fact of evolu- 

 tion is a settled one. We do not seek further evidence concern- 

 ing this fact although such evidence is piling up mountain high 

 as the result of every investigation which we have undertaken. 

 Every available line of argument leads directly to this conclusion. 

 To be sure the causes and the manner in which evolution works is 

 by no means clearly understood. Neither is the manner in which 

 radioactivity operates clearly understood. But the investigations 

 in radioactivity for example have merely lead us to a new con- 

 ception of the doctrine of the conservation of matter, not to its 

 overthrow. So we may regard the evolution doctrine as estab- 

 lished though we still search for information as to the details of 

 its processes. 



At the present time there are four fields in zoological science 

 in which research is particularly active. These are the study of 

 heredity (genetics) ; of the cell both as the physical basis of hered- 

 ity and as the seat of the physico-chemical phenomena associated 

 with life itself (cytology and general physiology) and the study of 

 internal secretions or hormones and their effects (endocrinology). 



