USEFUL AETS. 



CHAPTER VL 



SPIRAL AND RINGED TISSUES.— VARIOUS SPRINGS IN NATURE 



AND ART. 



Spiral Tissues, and their Structure and Uses. — The movable Gas-lamp. — Elastic 

 Tubes. — Breathing-tubes of Insects, and their Spiral "Wire. — Ringed Tissues 

 and their varied Structure. — Ringed Tissues applied to modern Dress. — 

 Chinese and Japanese Lanterns. — Proboscis of the House-fly. — Trachea of 

 various Animals. — Mutual Tendency of Rings and Spirals towards each 

 other. — Fibres of the Yew-tree. — Diving and Divers. — Principle of the 

 Diving-bell. — How it is supplied with Air. — Structure of the Air-tubes. — 

 Nests of the Water-spider. — Diving by means of Tubes. — Larva of the 

 Drone-fly, and its Mode of breathing. — How to examine them. — Leaping 

 Springs. — The Skip-jack in Nature and Art. — Skip-jack or Click Beetles. — The 

 Spring-tail, Grasshopper, Kangaroo, Gerboa, and other Jumping Creatures, 



Spiral and Ringed Tissues. 



WE have now to consider the Spiral Tissue under another 

 aspect, i.e. that of acting as the internal support of an 

 exterior membrane. Ringed tissues are necessarily conjoined 

 with the Spiral, as they both discharge the same office, and in 

 some cases merge almost imperceptibly into each other in the 

 same specimens. This is most beautifully shown in the pro- 

 boscis of the common House-fly, to which reference will pre- 

 sently be made. 



The subject is so large that only a comparatively small selec- 

 tion of examples can be made, the greater number belonging 

 to Nature, and not to Art. 



We will first take the common movable Gas-lamp^ with 

 its accompanying tube. It is at present the tube of which 

 we have to treat, the gas itself being reserved for a future 

 page. 



It is necessary that, in order to enable the lamp to be moved 

 from one spot to another, the tube through which the gas 



