PREFACE 



Of_all the laboratory mammals, probably none has contributed more 

 to the'*advancement of knowledge than the common mouse. Certainly 

 among all the mammals it is the most widely used, for not less than one 

 million mice are raised each year in this country for research in bac- 

 teriology, cancer and genetics. 



A result of this extensive use of the mouse is that a large body of 

 information has grown up concerning it. This, however, is so widely 

 scattered through the literature that it is often a major undertaking for 

 the research worker who wishes to use it to locate and gather the par- 

 ticular facts that he needs. Much of this information is assembled in this 

 book. In a number of cases, where there are important gaps in the 

 literature, these have been filled in by special research projects. In 

 general, controversial material has been avoided or given only brief 

 mention. The emphasis is placed on established facts useful to the 

 research worker. 



Certain fields, for example anatomy and endocrinology, have of neces- 

 sity been largely omitted. In most cases material omitted is adequately 

 covered in other recent books. 



Because it deals with the mouse alone, this book presents a vertical 

 cross-section of biological knowledge rather than the more usual horizontal 

 cross-section. It contains information about one animal drawn from 

 various branches of zoology, rather than information about one branch of 

 zoology drawn from observation of a variety of animals. There is, I 

 believe, one notable virtue in this vertical method of presentation, 

 namely, that it makes the synthesis of biological knowledge somewhat 

 easier. There is a widespread feeling among biologists that progress will 

 depend increasingly on the synthesis of the specialized techniques which 

 have been developed within the individual cubby-holes into which science 

 is somewhat arbitrarily divided. The departmentalization of biology is a 

 convenience not to say an absolute necessity, but within the organism the 

 tissues, the genes, the endocrines, the diseases and the processes of develop- 

 ment are all intimately related, and the biologist frequently finds that 

 research in his own specialty is leading him straight into another field of 



