116 VIEWS OF THE MICROSCOPIC WORLD. 



CHAPTER VI 



PARTS OF INSECTS, AND MISCELLANEOUS OBJECTS. 



Insects and mites, of mean degree, 



That swarm in myriads o'er the land, 



Moulded by Wisdom's artful hand, 



And curled and painted with a various dye ; 



In your innumerable forms 



Praise Him that wears th' ethereal crown, 



And bends His lofty counsels down 



To despicable worms. WATTS. 



EYES. Nothing within the whole range of his investigations has more elicited 

 the admiration of the philosopher, than the wondrous structure of the human 

 eye. Exceedingly complex in all its arrangements, it abounds with exquisite 

 contrivances for securing, under every circumstance, distinct vision ; and so 

 complete are the several parts in themselves, and so admirably adapted to each 

 other, that it is justly deemed the most perfect of all optical instruments. 

 Upon its curved and crystal front, fall the rays of light from unnumbered objects, 

 spread over a landscape miles and leagues in extent ; and the luminous lines 

 converging in the eye with unerring accuracy to the interior surface, form a 

 faithful picture of the entire scene, within the compass of a finger-nail. Perhaps 

 a vast city is immediately before it, with its splendid panorama of towers and 

 turrets, spires and cupolas, piles of massive buildings and thronged streets ; 

 while beyond, the harbor is crowded with the barks of commerce, and bays, and 

 misty isles stretch away in the dim distance ; yet all these are perfectly delin- 

 eated upon the retina, in their just proportions and natural colors. 



But if our wonder is excited when contemplating the structure of the eye 

 of man, and of other animals, it is still more heightened upon examining the 

 visual organs of insects, beneath the powerful glasses of the microscope. The 

 eyes of insects differ from those of other animated existences, chiefly in respect 

 to number, form and arrangement. In some, as in the spider, the number varies 

 from six to eight, possessing such a diversity in their mutual arrangement, that 

 their relative positions have been employed by writers to designate the several 

 species. Thus, in one kind the eyes are arranged as in figure 183 ; in another 

 as shown in figure 184 ; and in a third according to figure 185, and so on. 



Fig. 183. Fig. 184. Fig. 185. 



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