vi INTRODUCTION. 



introduction to the study of so highly modified a type as the 

 Blovv-fiy. I have therefore followed the example of Straus 

 Durckheim, and given a resume of the principles of anatomy, 

 morphology, and histology, applied to insects generally in a 

 series of introductory chapters and sections, in order that the 

 most recent knowledge collected by many observers may be 

 presented to my readers, and enable them to understand more 

 completely the characteristic peculiarities of the very remark- 

 able type I propose to describe, and its relations to other forms 

 of insect life. 



The term ' Blow-fly ' is applied indiscriminately, not only to 

 several species of a single genus, but to those of other genera 

 and sub-genera. M)^ own researches, which have extended 

 over nearly a quarter of a century, have been chiefly made 

 upon the most abundant form in this country, Calliphora ery- 

 throcephala, and when I speak of the Blow-fly in the following 

 pages, unless otherwise stated, my observations refer to this 

 species only. 



During the past two years most of my researches have been 

 made in my new laboratory at the Middlesex Hospital Medical 

 School. I am indebted to my Demonstrator, Mr. G. C. Karop, 

 for valuable help, and more especially for the trouble he has 

 taken in correcting my proofs, and to Mr. A. W. Kappel, the sub- 

 librarian of the Linnean Society, for the zeal he has shown in 

 searching out and obtaining for me many of the works I have 

 consulted. 



