INTRODUCTION 



The development of the biological sciences has been largely through 

 the observational method. In the nineteenth century descriptive biologists 

 came to occupy a preeminent and leading position in the field of biology. 

 With the advent of the twentieth century, however, biology began to 

 emphasize the experimental; and today, biology is an experimental science 

 in practically all of its branches. However, experimentation in animal 

 biology has very largely concentrated on a relatively few species which 

 have come to be classic. These animals were selected because of their 

 tractability and availability, and because of the fund of existing knowledge 

 about them. Therefore, animal experimental biology has been largely 

 oriented around the dog, cat, rabbit, mouse, guinea pig, and white rat. 

 Despite the fact that again and again it has become obvious that there 

 are wide varieties of metabolic patterns and inter-specific difl^erences in 

 physiology as well as morphology, the bulk of experimentation continues 

 to be done with relatively few classic types. Despite this concentration of 

 effort, over the years numerous researchers have investigated the use of 

 different animals for experimental purposes, including mammals ranging 

 from aardvarks to zebras. 



The writings of these investigators, however, are scattered widely both 

 in literature and in time, making it diflScult for an experimental biologist 

 to draw on the fund of already available knowledge about animals other 

 than those most frequently used. The basic thesis guiding the preparation 

 of "Physiological Mammalogy" has been to make available to the experi- 

 mental biologist the wealth of data in the work of widely geographically 

 scattered research scientists of diverse experimental interests. 



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