CHAPTER Vril 

 METHODS OF INSECT HISTOLOGY. 

 INTRODUCTION. 



The study of the gross anatomy of most insects requires 

 no more in the way of equipment than a simple dissecting 

 outfit, — viz., scalpels, scissors, needles, and dissecting tray; 

 and little more in the way of method than skilful manipula- 

 tion of these simple tools. But for the study of the anatomy 

 of very small insects, and more especially for the study of 

 the histology of insect organs, the character of the various 

 body-tissues, the histolytic and histogenetic phenomena ac 

 companying the post-embryOnal growth of insects with com- 

 plete metamorphosis, and, finally, for the study of insect 

 embryology, a more elaborate equipment is required, and 

 some knowledge of the special methods of the animal his- 

 tologist is needed. 



Insects present a special problem in histologic method 

 because of the always present covering of chitin which pro- 

 tects their bodies. This chitinous wall hinders very effect- 

 ively the penetration of the fixing fiuids-and besides presents 

 very serious difficulties in section cutting. Hence even the 

 stuclent already familiar with the usual methods of animal 

 histology needs some special guiding in beginning the study 

 of insect histology. 



The following notes are intentled to furnish a guide for 

 beginning students of insect histology and development. 



