32 OLAIinE FUr.LKR. 



Tlio niiiil furrow appears as a crease or fold after the final 

 moult. 



V. THE KESPTKATORY SYSTEM. 



Plates TTI to Y, fio-s. 2-48. 



As the wiiio- trachofB (levelo]i from trachefP of the body, their 

 genesis and growtli and their diversified development may 

 he hotter examined with some knowledge of the stem fi'om 

 which they spring and of tracheal growth and development 

 occnri'ing before they are produced. This involves a stndy of 

 the respiratory system and its development. Natnrally, the 

 oldest tracheae are those jiresent in embryo ; bnt, as these were 

 not easily observed, the veiy young nymphs were examined. 



It was my intention to base this chapter npon the tracheae 

 of the youngest forms of either Calotermes dnrbanensis 

 or of Cryptotermes fip. ; \mt in them the cardinal natal 

 stem and its immediate development are too complicated to 

 follow and to describe, although they can be understood with 

 a knowledge of the simpler stem of the Metatermitida^. 

 Subsequently (Section Y, f), a short comparison is furnished 

 which deals with the points of difference found between the 

 two forms. The present account relates to the simpler stem 

 and some of its simpler post-embryonic developments, as 

 observed in Termes natalensis, Odontotermes late- 

 ricius, 0. badius, Microtermes incertus, and Eu- 

 termes (trinervins group). 



When these insects emerge from the eg;g they are provided 

 with a respiratory system resembling a long, narrow crate, 

 with ladder-like sides and bottom, with an open to]i and ends 

 and possessing a few paired extensions. The whole is remark- 

 ably destitute of branchlets, and there are none of those 

 arborescent trachea^ which develop later, and, to a great 

 extent, shroud it. 



The air enters through ten pairs of spiracles, two thoracic, 

 and eight abdominal, and from the spiracles it passes into the 



