1868.] PARKES — RESPIRATION OF INSECTS. 427 



But what of the termination, — the ultimate distribution of these 

 elaborately constructed tubes ? And what of the purpose they 

 are intended to subserve ? With regard to their distribution ; no 

 one, perhaps, has gone so far in demonstrating their universality and 

 extreme fineness, as Dr. Beale, with his 25th-inch object glass, and 

 with this, which gives a magnifying power of nearly 3000 diameters, 

 he has traced both air tubes and nerve fibres interlacing and 

 spreading over the sarcolemma of muscular fibre, taken from the 

 larva of the blow fly, a single fibre of this insect's muscle being 

 completely encased in a net work of these inconceiveable minute 

 and wondrous air tubes, whose very existence requires a power 

 of 3000 diameters to reveal? 



And not only do they thus intertwine about the fibres of an 

 insect's muscles, but they penetrate the very substance of the 

 nerve ganglia of the body; entering the head, and spreading over 

 that optic nerve which receives impressions through ten thousand 

 compound eye lenses ; penetrating the wings, and giving lightness 

 and energy to those untiring organs of flight ; spreading over the 

 stomach and other abdominal viscera ; and aerating every particle 

 of that blood which bathes and surrounds all the internal organs ! 

 I know not, gentlemen, what your feelings may be when yon 

 examine with your microscopes such unspeakably wonderful and 

 complicated organisms, condensed and crowded within an almost 

 invisible point of space ; and this mechanism vitalized, directed 

 and controlled during the period of its existence by an individual 

 will, and by an unerring instinct. I know not, I say, what you may 

 think and feel about the origiu and design of such manifestations 

 of constructive wisdom and skill ; but for myself, I can say, it 

 produces in my mind the most profound emotions of humility 

 and awe ; nay, rather, I would say, of adoring gratitude to that 

 Infinite Being, who, while he displays to my astonished sight a 

 spectacle so grand and glorious, as I look through my telescope 

 at a starry universe, has also stooped so low, as to lay at my very 

 feet the same incontestible proofs of His own " Infinite power 

 and Godhead." 



But what of the Physiological necessity for such a complicated 

 mechanism ? Can we suppose that the mere general aeration of 

 the blood, such as is supposed to take place in the pulmonary 

 respiration of higher animals, calls for this excessive elaboration 

 and minute sub-division of air tubes in the insect economy. 

 These tubes penetrate and twine about the interior of organs, 



