166 Life and Immortality, 
thread is wound round and round the nest in a horizontal 
direction, and when freshly spun is found to consist of six 
or eight very thin transparent fibres, which have alternated 
tapering ends where they are broken off. Very soon after 
the thread is spun, particles of dirt adhere to it, and render it 
difficult to interpret its character. The nest measures one- 
half of an inch in height, and three-cighths in diameter. 
The time occupied in collecting materials and constructing 
the nest is about four hours, and when all is ready the male 
starts out to seek a female, and, having found her, conducts 
her with many polite attentions to the prepared home. The 
eggs being deposited, the male establishes himselfas a guardian 
of the precious treasures, not even suffering the female to 
approach it again. Every fish that comes near, no matter 
how large, is furiously assailed. He gives battle valiantly, 
striking at their eyes and seizing their fins in his mouth. 
His sharp dorsal and ventral spines are very effective weapons 
in his defence. Constant watchfulness upon the part of the 
male is needed, for, if he go away for only a few moments, 
the sticklebacks and other fish lurking in the vicinity rush 
in and devour the eggs in an instant. A whole month he is 
occupied in providing for the safety of his offspring. About 
the tenth day he employs himself in tearing down the nest 
and carrying the material to some little distance. The fry 
may now be observed in motion. And these the male con- 
tinually nurses, suffering no encroachment, and if the young 
brood show a tendency to stray beyond bounds, they are 
driven back within their precincts, until they are strong 
enough to provide for their own living, when both old and 
young disappear together. 
But nothing in the lives of all these little nest-builders is 
more interesting than the intelligence they display and the 
facility with which they adapt themselves to circumstances. 
They seem to be able to grasp almost instantly the conditions 
of the environment, and to employ a wise discrimination in 
suiting them to their wants. Hardly two nests are alike. 
