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INTRODUCTION 



Small rodents will always find a place in the laboratory of 

 the zoology teacher, the biological investigator, the medical 

 researcher, and the fancier. Each man has different problems 

 in mind: behavior, physiology, disease, and beauty among 

 others. 



On account of certain innate qualities the house mouse, 

 Mus musculus, has become in many ways the laboratory 

 mammal most favorable for culturing. Its fertility, prolific- 

 ity, convenient size, short gestation period, its manifold 

 variations, inexpensive maintenance, resistance to open in- 

 fections, susceptibility to certain diseases, and ease of produc- 

 tion conspire to make it the laboratory animal par excellence. 

 The teacher of zoology uses variations of the house mouse 

 to demonstrate the laws of heredity, the biological investi- 

 gator employs them for physiological and genetic studies, 

 the advanced medical man uses them as media in which to 

 culture disease germs or for pathological tests as in the pro- 

 duction of sera, and the fancier prizes them for their aesthetic 

 appeal. 



Literature upon the house mouse, its origin, history, 

 distribution, development, the nature of its variations, 

 the hereditary transmission of its varietal characters, and 

 methods of rearing it suitable for the needs of laboratories, 

 has not been assembled so far as I am aware. . The data are 

 in some instances rare, usually widely scattered, and often 

 inaccessible to those who could advantageously employ 

 them. Some are recorded in difficult and highly technical 

 language. Some of the data have never been published. 



To collect such valuable information as this concern- 

 ing the house mouse and to present it in a usable form is 

 the task of this book. 



