12 



PRINCIPLES OF ANIMAL BIOLOGY 



represents on the whole the simplest phase of investigation, since it is 

 possible to observe without any anticipation of the phenomena to be 

 observed. The use of experiment is a later development in each field. 

 It impUes looking forward to a result, and the experimenter must formu- 

 late some problem and adopt a suitable procedure for its solution. Any 

 branch of investigation, therefore, in wliich the experimental method is 

 apphcable may be regarded as mature or youthful, according as experi- 

 ment has or has not come into common use. At the time of which we 

 write, experiment had long been used in physics and chemistry. Experi- 

 ment had been used occasionally in zoology even as early as Aristotle, 



Fig. 3. — William Harvey, 1578-1657. (From Garrison's History of Medicine.) 



liut had been long since forgotten as a method. Its restoration was in 

 large part due to the efforts of WilUam Harvey, of England (1578-1657) 

 (Fig. 3). Harv^ey is best known as a physiologist, sometimes called 

 the founder of physiolog}'. He is credited with the discovery of the 

 circulation of the blood, though his claim to this honor has been disputed. 

 Although in an account of the rise of physiology, which occupied centuries, 

 Harvey would figure prominently in the earl}' period, it is not indefensible 

 to state that his chief service to zoology was not in his contribution to 

 physiology but in his frequent use of the method of experiment. In 

 his work in physiology he directly affected only one field of zoologj'; 

 but in his adoption of the experimental method he influenced every 

 branch of the science. For all of the zoological sciences today employ 

 experiment as an important mode of investigation. 



