PREFACE. 



In 1870 I published a small treatise on the ' Anatomy of the 

 Blow- Fly.' This has now been out of print for nearly ten years. 

 In 1890, when I undertook the present work, a book of about 

 300 pages was contemplated ; since then, however, it has grown 

 to more than twice that size, and it has been found necessary 

 to divide it into two volumes. 



The present volume deals with the subject generally — with 

 the anatomy of the larva and the development of the embryo 

 in the egg and of the nymph in the pupa, as well as with the 

 external skeleton and histology of the perfect insect. The 

 second volume will consist of a detailed description of the 

 various internal organs, their development and physiology. 

 The issue of the parts of this volume has been unavoidably 

 delayed. The introduction and the first four chapters appeared 

 in October, i8go, the fifth chapter in April, i8gi, and the 

 remainder in April, 1892. 



It is hardly to be expected that a work of the present magni- 

 tude can be without errors, but I trust that any which may 

 be found will be unimportant. I have endeavoured to keep 

 matters of fact distinct from the hypotheses and conclusions 



