EXPERIMENTAL ZOOLOGY 



WINTERTON C. CURTIS 

 Professor of Zoology 



INTRODUCTION 



Until the latter years of the nineteenth century, zoologists 

 were largely engaged in the observational and descriptive study 

 of animal life and had paid little attention to the experimental 

 analysis of vital phenomena. While such studies are unsatis- 

 factory from our present standpoint, they are of the kind 

 usually undertaken during the formative period of any science, 

 and, since they have furnished a basis for important general- 

 izations, we should have no quarrel with our brethren of 

 these earlier years. 



Just what is meant by "observational" and "descriptive" 

 study may be illustrated within the field of anatomical science 

 in the following manner: An animal is like a complex 

 machine, capable of a variety of activities in its many parts 

 and of action as a unified whole. That which first attracts 

 our attention to the machine is what it can do, but, as soon 

 as we push our examination further and attempt to learn how 

 the unified work of the machine is accomplished, it becomes 

 necessary for us to understand the complex of parts, to study 

 its anatomy that we may explain the working of the mechan- 

 ism. In a similar manner, the functioning of the animal 

 mechanism, what it could do as a whole, was doubtless com- 

 mon knowledge from the beginning of human intelligence, 

 while the attempt to learn in detail how the animal mechanism 

 works, to really analyze the phenomena, is of later origin 

 and had its beginning in the domain of medicine. As the 

 anatomical studies of the medical men were followed further, 



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