18 ^ 
FIFTEEN-SPIKED STICKLEBACK. 
and if the guardian is forced to retreat by the receding of 
the tide, he returns as soon as the way is open, and for three 
or four weeks he continues his guard, until the young are 
able of themselves to take their chance in the broad expanse 
of sea. So much is he intent on the principal object of his 
solicitude, that at this time himself may be easily caught; hut 
he resents every interference with the nest; and if the grains 
of ova he exposed to sight, as was done by way of trial, the 
breach was immediately repaired by the labour of dragging 
the materials into a position by which they are again concealed 
and protected. 
A singular instance of constructive skill and patience in the 
formation of its nest, which occurred within my knowledge, is 
deserving of remembrance. The situation selected was the 
loose end of a rope, from which the separated strands hung 
at about a yard from the surface, over a depth of four or 
five fathoms; and to which the materials could only have been 
brought, of course in the mouth of the fish, from the distance 
of about thirty feet. They were formed of the usual aggregation 
of the finer sorts of green and red ore-weed; but they were 
so matted together in the hollow formed by the untwisted 
strands of the rope, that the mass constituted an oblong ball 
of nearly the size of the fist; in which had been deposited 
the scattered assemblages of spawn, and which was bound into 
shape with the thread of animal substance already described, and 
which was passed through and through in various directions, 
while the rope itself formed an outside covering to the whole. 
We can scarcely suppose that such a nest can have been the 
work of more than a couple of fishes, but the grains of 
spawn had grown to almost the size of radish seeds, and in 
collective bulk seemed greatly disproportionate to the size of 
the parent, and only to be explained by the well-known fact, 
that the ova of fishes generally obtain an increase of bulk by 
the absorption of water after exclusion; which fluid may be 
supposed to exert considerable influence on the further de- 
velopment of the young. The embryo of this fish, as is 
believed to be the case with many others, is not found to 
bear a close resemblance to the parent, and, in fact, may be 
said to pass through a decided metamorphosis in the course 
of its final development. 
