584 HOMES WITHOUT HANDS. 



oue resident in tropical countries seems to have the energy to 

 conduct a series of experiments which would involve expendi- 

 ture of time and labour. Travellers and residents in tropical 

 countries are often admirable collectors, but, with few exceptions, 

 are poor observers, except of facts that pass immediately under 

 their observation. They make valuable collections, and record 

 many useful isolated facts ; but, unfortunately, they seldom 

 appear able to carry on a series of experiments that would 

 occupy several successive years, and thus we lose much valuable 

 as well as interesting knowledge, and waste much time in trying 

 to discover by inference that which we ought to know from 

 observation. 



The last point which will be noticed in connexion with this 

 remarkable cell-group is, that it is perfectly protected from rain. 

 Slight and delicate as is the structure, appearing scarcely thicker 

 than the silver paper with which engravings are guarded, it may be 

 deluged with water without being wetted. Over the whole of 

 the cells the insect contrives to lay a thick coat of some varnish- 

 like substance, which at the same time gives the exterior of the 

 cells a polish, binds them more firmly together, and renders 

 them waterproof. The varnish is nearly transparent, but has 

 a blackish hue, which gives to the whole cell-group a uni- 

 fonnity of aspect which would be wanting if the protecting 

 substance were itself colourless. 



The insect is, at first sight, black in colour, as is expressed by 

 its specific title. A closer examination in a more favourable 

 light shows that the true colour is a green so deep as to appear 

 black, but having a perceptible bronze gloss in certain lights. 

 The wings are equally sombre in aspect, looking as if they had 

 been held above the flame of a badly-trimmed lamp, and 

 received all the soot upon their translucent membranes. Indeed, 

 tlieir peculiar colour can only be expressed by the word 

 " smoky." 



It is hardly possible to overrate the wonderful varieties of 

 form that are assumed by the nests of insects, — varieties so 

 bold and so startling that few would believe in the possibility 

 of their existence without ocular demonstration. No rule seems 

 to be observed in them ; at all events no rule has, as yet, been 

 discovered by which their formation is guided; neitlier has 



