580 THE MICROSCOPE. 



largest it extends beyond the limits of our comprehension, 

 escapes our researches in the smallest. If, while we dis- 

 sect with care the larger animals, we are filled with wonder 

 at the elegant disposition of their limbs, the inimitable 

 order of their muscles, and the regular direction of their 

 veins, arteries, and nerves, to what a height is our astonish- 

 ment raised when we discover all these parts arranged in 

 the least of them in the same regular manner ! How is 

 it possible but that we must stand amazed, when we reflect 

 that those little animals, whose bodies are smaller than the 

 point of the dissecting knife, have muscles, veins, arteries, 

 and every other part common to large animals ! Crea- 

 tures so very diminutive that our hands are not delicate 

 enough to manage, nor our eyes sufficiently acute to see 

 them." 



The Articulate sub-kingdom, Insect a, is divided and 

 sub-divided into orders, families, genera, species, as for 

 example : — 



Lepidoptera ; typical form, Butterfly, Moth. 



Dipteria; 1 typical form, Fly, Gnat, &c. 



Aptera ; typical form, Flea, Louse, Springtail. 



Coleoptera ; typical form, Beetle, Water Beetle, &c. 



Orthoptara ; typical form, Locust, Grasshopper. 



Neuroptera ; typical form, Dragon-fly, May- fly. 



Hymenoptera ; typical form, Bee, "Wasp, Ant. 



Homoptera ; typical form, Plant-louse (Aphis), Lan- 

 tern-fly. 



Ilemiptera ; typical form, Water-scorpion, Water-boat- 

 man. 



Arachnida ; typical form, Spider, Scorpion, &c. The 

 Acarina belong to this genus, family Acarea, well known 

 as "Mites" and "Ticks." 



Insects are characterised by a simple breathing ap- 

 paratus ; by the division of the body into distinct regions 

 or segments ; when three, the middle one, the thorax, 

 bears three pahs of jointed legs, and usually two pairs 

 of wings ; and by the possession of a single pair of jointed 



(1) Comprised within the order Diptera, or two-winged flies, are several 

 genera having no wings, the apterous and suctorial Pulex, and the apterous and 

 pupiparous Episboscidce : among the latter, we have the winged Hippobosea, 01 

 horse -fly, and some others. 



