836 THE POPULAR SCIENCE MONTHLY. 



feel sure it is a neat and appropriate epithet.) Where the chances of 

 infant mortality rule high, the mother-animal must produce vast num- 

 bers of small and ill-supplied eggs in order to provide against the ad- 

 verse possibilities. That careless parent, the cod, who lays her spawn 

 unprotected upon the shallow banks, for thousands of greedy enemies 

 to devour, often produces at a single birth as many as from four to 

 nine million separate eggs. But just in proportion as the eggs and 

 young are more efficiently guarded and provided for in life does it 

 become possible to economize in the number of germs originally pro- 

 duced, and to give each at the outset a fair supply of yolk to start 

 well in life with. Compare the myriad tiny black seeds of the poppy, 

 which take their even chances anywhere that fate may carry them, 

 with the richly stored bean or pea or filbert, well provided with nutri- 

 ment for the growing seedling, and you will see at once the force of 

 the analogy here intended. The codfish lays a great many ill-supplied 

 eggs, and lets them shift for themselves in the open sea as best they 

 may, on the off chance of one among four million or so reaching ma- 

 turity ; the stickleback lays comparatively few large and well-supplied 

 eggs, but the amiable father watches with tender solicitude over the 

 safety of all, so that on an average two at least out of each mother's 

 small brood must needs survive to years of adult sticklebackhood. 



I have spoken of the stickleback genus so far as though, like the 

 French Republic, it were one and indivisible. Such, however, is not 

 the case. The family has split up into several minor sections, each 

 adapted to particular situations. There are some ten known species 

 of stickleback, and the facts hitherto noted apply most especially (save 

 in a few instances) to one above all others among them, the common 

 British three-spined stickleback. All the varieties are pretty much 

 alike in all essential points, having the same long, flat-sided bodies, 

 with hard cheeks, while parts of the skeleton usually form an external 

 coat of mail, and grow out into large scutes or shields along the sides. 

 On their back are more or fewer of the spines from which the entire 

 group take their generic name, nine in one species, fifteen in another, 

 three only in the commonest English form, and no more than two in 

 the pretty little North American example. One of them has adapted 

 itself to brackish water and the open sea ; the others are all fresh- 

 water forms, though most of them at a pinch can manage a sea-voyage 

 without serious damage to their constitutions. They are a north tem- 

 perate family by origin ; in other words, they have sprung up in the 

 rivers of the sub-Arctic zone, and have not yet spread beyond the 

 Arctic and temperate regions of the northern hemisphere on both sides 

 of the Atlantic. 



Our common little British river stickleback, the familiar tittlebat 

 of the Serpentine and the Hampstead Ponds, is the three-spined form 

 ( Gastrosteus aculeatus) ; and he has generally, in addition to his offen- 

 sive spines, a series of defensive shields or plates along the gleaming 



