60 lIs'TEKNAI. ANATOilY OF THE IMAGO. 



CHAPTER IX. 



INTERNAL ANATOMY OF THE IMAGO. 



Our apology for not proposing to speak more at length 

 in this connection, of the internal anatomy of the insect, 

 is that this outline is especially intended as a guide to 

 the object study of the insect itself^ as we may observe it, 

 without the aid of a dissecting knife, in Xatur ? about us. 



This department, however, arranges itself under the 

 heads of the generative, digestwe, respiratory, circulatory, 

 muscular or tnotive, and sensitive and 7iervoiis systems. 



Of the generation or (ieye^opmen^of the insect we have 

 already spoken quite at length, under the heads of eg^ 

 hxrvse and pupa?, and the structure of the organs of 

 oviposition. 



The digestive organs consist of a long tube of different 

 sizes, termed the alimentary canal ; the several parts of 

 it are the pharynx and mouth, the oesophagus, the craw, 

 the gizzard, the stomach and the intestines ; there are 

 also biliary tubes, salivary glands and other special 

 organs. 



Respiration. — Insects breathe by means of two great 

 tubes that extend along the sides of the body and give 

 out to each abdominal ring two branches called spiracles, 

 and these, through the stomata or breathing mouths at 

 the sides of each ring, inhale and exhale the air. 



From these trachejie also pass out many little tubes 

 that enter into all parts of the body, even between the 

 muscles, and so aerate or rather oxygenate the blood. 



