244 ANIMAL INTELLIGENCE. 



away to a safe distance ; then, after patting down the nest, he 

 proceeds in search of another female. The nest is built and the 

 ova deposited in about twenty-four hours. The male continued 

 to watch it day and night, and during the light hours he also 

 continually added to the nest. 



The marine fifteen-spined stickleback(Gasterosteus spinachia) 

 affords another instance of nest-constructing fishes. The places 

 selected for their nests are usually harbours, or some sheltered 

 spots to where pure sea water reaches. The fish either find 

 growing, or even collect some of the softer kinds of green or red 

 seaweed, and join them with so much of the coralline tufts 

 (Janite) growing on the rock as will serve the purpose of afford- 

 ing firmness to the structure, and constitute a pear-shaped mass 

 five or six inches long, and about as stout as a man's fist. A 

 thread, which is elastic and resembles silk, is employed for the 

 purpose of binding the materials together : under a magnifier 

 it appears to consist of several strands connected by a gluey 

 substance, which hardens by exposure to the water. 1 



M. Carbonnier, who has studied the habits of the Chinese 

 butterfly-fish (Macropodus) in his private aquarium in Paris, 

 where he had some in confinement, observed that the male 

 constructs a nest of froth of considerable size, 15 to 18 centi- 

 metres horizontal diameter, and 10 to 12 high. He prepares 

 the bubbles in the air (which he sucks in and then expels), 

 strengthening them with mucous matter from his mouth, and 

 brings them into the nest. Sometimes the buccal secretion 

 will fail him, whereupon he goes to the bottom in search of 

 confervse, which he sucks and bites for a little in order to stimu- 

 late the act of secretion. The nest prepared, the female is in- 

 duced to enter. Not less curious is the way in which the male 

 brings the eggs from the bottom into the nest. He appears 

 unable to carry them up in his mouth ; instead of this, he first 

 swallows an abundant supply of air, then descending, he places 

 himself beneath the eggs, and suddenly, by a violent contraction 

 of the muscles in the interior of his mouth and pharynx, he ex- 

 hales the air which he had accumulated by the gills. This 

 air, finely divided by the lamellse and fringes of the gills, 

 escapes in the form of two jets of veritable gaseous powder, 

 which envelopes the eggs and raises them to the surface. In 

 this manoeuvre the Macropodus entirely disappeared in a kind 

 of air-mist, and when this had dissipated he reappeared with a 



1 Quoted from Francis Day, F.L.S., ' Instincts and Emotions of Fish,' 

 Journ. Linn. Soc., vol. xv., pp. 36-7, where see for other cases of nest- 

 building among fish. 



