TRANSACTIONS OF THE SOCIETY. 



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Monthly Meeting held on November 12th, 1889, Mr. J. White- 

 head, Vice-President, in the chair. 



There was a good attendance of members, and a few 

 visitors. Two gentlemen — Kev. G. Kobins, and Mr. James 

 Mourantjun., — having been proposed for election as members 

 of the Society, the real business of the evening began. Mr. 

 E. D. Marquand read a most interesting and instructive paper 

 entitled " How Insects Breathe " : — 



Insects having no lungs or analogous organs, their respiration 

 differs entirely from that of the higher animals ; and further — a 

 point which was too frequently overlooked — insects never breathe 

 through the mouth. Although there is great uniformity in the 

 general plan as regards the breathing apparatus of insects, there is 

 an almost infinite variety in its details ; but in the most common and 

 typical forms the aeration of the blood is provided for by the intro- 

 duction of air into every part of the body through a system of 

 minutely distributed airtubes, which penetrate even the smallest and 

 most delicate organs ; and the outer air enters these tubes through a 

 series of tiny holes or spiracles which are placed on each side of the 

 body. One of the simplest forms of spiracle is that of a caterpillar, 

 the whole series of which — nine on each side — are easily seen with 

 a hand-lens. It consists merely of a cleft membrane, and the cater- 

 pillar has the power of opening and closing these apertures at will. 

 The spiracle of the common housefly is a much more complex affair, 

 a beautiful interlacement of branches, like miniature trees, springing 

 from the edges of the outer ring — a perfect network of filaments, 

 interwoven so intricately that no drawing can adequately represent 

 it. In the larva of the common cockchafer the spiracle takes the 

 form of a kind of sieve of extreme fineness. In the larva of the 

 cranefly the centre of the spiracle is occupied by an impervious disc 

 from which radii stretch out to the margin — the one great object 

 aimed at and attained in every instance being the complete and 

 perfect exclusion of the most minute particles of dust or other 

 extraneous matter and yet the free admission of air. But besides 

 this wonderful contrivance there is yet a further provision of nature 



