TRANSACTIONS 



OF 



THE CROYDON MICROSCOPICAL AND 

 NATURAL HISTORY CLUB. 



1891-2. 



93. — Kespiration of Insf.cts. 



By C. H. Goodman. 



(Read March 11th, 1891.) 



In dealing witli this comprehensive subject this evening it will 

 be necessary to omit all reference to the theory of respiration in 

 general, and proceed at once to examine the methods by which 

 it is effected. Assuming therefore that you recognise the neces- 

 sity of bringing the oxygen of the atmosphere into contact with 

 the blood so as to vitalise every structure in the body, we will 

 first notice the modes adopted in the different groups of the 

 Arthropoda. This is seen in the following table : — 



p fin the lower — cutaneous, 



[but mostly — branchiate. 



(cutaneous, 

 branchiate, 

 tracheate. 

 Myriopoda . . ... tracheate. 

 Insecta ... ... tracheate. 



Here a gradual development is seen, the Insecta attaining the 

 highest positio]!. 



The general plan of the tracheal system, as found in insects, 

 may be said to consist of two main tubes extending down either 

 side of the body, often united at intervals by connecting ones. 

 Smaller branches ramify from every part in all directions, 

 gradually dwindling away as they penetrate further, and spread 

 over every organ. Lateral branches from the main tubes, or 

 trachefe, lead to the external surface, where air is inspired 



