140 THE INDUSTRIES OF ANIMALS. 



enclose the eggs of the queen with a provision of 

 honey. 



I do not wish to insist on creations of this kind 

 which are independent of the animal's will and re- 

 flection. Near these facts must be placed those in 

 which animals, still using a natural secretion, yet 

 endeavour to obtain ingenious advantages from it 

 unknown by related species. 



There is, for example, the Macropus viridi-auratus, 

 or Paradise-fish, which blows air bubbles in the mucus 

 produced from its mouth. This mucus becomes fairly 

 resistant, and all the bubbles imprisoned and sticking 

 [Side by side at last form a floor. It 

 I is beneath this floating shelter that 

 the fish suspends its eggs for its 

 little ones to undergo their early 

 development. 



Animals who increase theirna- 

 tural protection by the addition of 

 foreign bodies. — Certain tubicolar 

 Annelids, whose skin furnishes 

 abundant mucus which does not 

 become sufficiently hard to form an efficacious pro- 

 tection, utilise it to weld together and unite around 

 them neighbouring substances, grains of sand, frag- 

 ments of shell, etc. They thus construct a case 

 which both resembles formations by special organs 

 and manufacture by the aid of foreign materials. 

 The larvae of Phryganea, who lead an aquatic life, use 

 this method to separate themselves from the world 

 and prepare tubes in which to dwell. (Fig. i8.) 

 All the fragments carried down by the stream are 

 good for their labours on condition only that they are 

 denser than the water. They take possession of 



