62 MICROSCOPIC ILLUSTRATIONS. 



sists; for it cannot be denied that an aplanatic compound 

 microscope will exhibit these appearances with more 

 distinctness, and without any risk of killing or injuring 

 the object by exposure to the heat of the sun's rays 

 condensed upon it. 



As the creature continues growing, it assumes a va- 

 riety of colouring, and becomes more opaque as its 

 change approaches towards completion, which takes place 

 in a few months from the time it leaves the egg. The eyes 

 are reticulated, as represented in figure 4, plate 11, and 

 are of a citron colour ; while the body exhibits a most 

 beautiful play of different tints, and finally assumes that 

 of a rich brown, with various shadings. The large 

 air-vessel (trachea)* which runs along each side of the 

 body, together with its numerous ramifications traversing 

 the different membranous leaf-shaped paddles, are now 

 of a dark colour, and the elytra, or wing-cases of the 

 future insect, become daily more and more apparent. 



The magnified representation of the larva (fig. 4) was 

 taken just previous to its change to the perfect insect. 

 Fig 5. gives the real magnitude of the creature; and 

 fig. 6 exhibits a view of the perfect insect of the natural 

 size. 



During the infant state of this larva's existence it is 

 very transparent, displaying, under the microscope, in a 

 most surprising manner, the circulation of the blood. 



The systems of respiration and circulation in insects 

 differ most materially from those of the vertebrated ani- 



* The coat of this vessel differs from that of most larvae, a fact not 

 noticed by naturalists. 



