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LNATOMY AND PHYSIOLOGY OF INSECTS. 



HAVING thus traced the progress of insects from the 

 me of their hirth till they arrive at their full matu- 

 ity, and likewise noticed the most remarkable fea- 

 ares in their external conformation, it now becomes 

 equisite to advert to their internal structure, and 

 ive a comprehensive view of the complex system of 

 rgans by which life is maintained. In these a very 

 lose analogy, for the most part, exists to the vital 

 ystem of the higher animals ; but in some respects 

 urious and most important differences prevail. View- 

 ng the animal kingdom as forming a progressive 

 eries, from the most simple to the most complex 

 rganism, insects may be regarded as occupying 

 early the centre of the scale ; for, though some pro- 

 erties might entitle them to rank higher, there are 

 thers in which they are so deficient, as completely 

 o counterbalance that consideration. In muscular 

 igour, for example, and the complication of the 

 igestive canal, they are almost equal to the verte- 

 rata, while the circulating system is so imperfect, 

 hat it was, till lately, a matter of doubt whether it 

 .eserved the name. From these considerations, it 

 nay be inferred that the systems of organs are neither 

 'ery complex nor very simple, and that in these re- 

 pects, there is some degree of inequality among 

 hem. 



