826 THE POPULAR SCIENCE MONTHLY. 



practice, were accustomed to use their surplus catch as mamire, 

 placing a thousand fish to the acre. The Towsers of that day 

 evidently gave trouble, as would appear from the following quaint 

 and amusing town law of Ipswich passed in May, 1644 : 



" It is ordered that all Doggs for the space of three weeks after 

 the publishing hereof shall have one Legg Tyed up. If such a 

 Dogg should break loose and be founde in any Cornefielde doing 

 any harme, the Owner of the Dogg shall pay the Damage. If a 

 man refuse to tye up his Doggs legg and he be found scraping up 

 Fish in the Cornefielde, the Owner shall pay 125., besides whatever 

 Damage the Dogg doth." 



Of the shad, man, without doubt, is the greatest agent of de- 

 struction, although his wasting effort is exerted only within the 

 borders of his own domain ; but beyond, in the open sea, the ranks 

 of the migrating horde are thinned by the shark, porpoise, and 

 dogfish, the seal, otter, and salmon, and, most destructive of all, 

 the bluefish. This dread sea butcher works terrible havoc among 

 all neighboring fish not larger than himself, and in the shoals of 

 shad, like those of the menhaden, he revels in slaughter. His op- 

 portunity, however, is brief, and perhaps not frequently exercised 

 upon the incoming fish, his earliest appearance in our latitude be- 

 ing usually later than that of the shad. Along New Jersey, how- 

 ever, there have been instances of shoals of shad being driven 

 upon the shore by his murderous onslaughts, the bluefish being a 

 creature that often seems to chop, maim, and destroy for mere 

 amusement. 



The shad, after its entrance into our rivers, eats nothing, the 

 one all-dominating impulse being that of the maintenance of its 

 species ; for that it braves every danger and endures every hard- 

 ship. It presses on, sparing no exertion to attain its goal ; if it 

 halts or retreats, it is because the temperature of the river current 

 has fallen too low for the development of its ova. It manifests an 

 acute discrimination of gradations of heat, recognizing promptly 

 differences of a degree or even less. In spawning it seeks a tem- 

 perature of about 60, and usually deposits its eggs near sunset, 

 when the water is warmest, the place chosen being often the down- 

 stream edge of wide flats, over which the gently flowing current 

 becomes heated to the requisite point. That current thencefor- 

 ward becomes the foster mother of the deposited ova, its suspended 

 oxygen ever vivifying the slowly developing germ, and, thus cared 

 for, the abandoned and apparently neglected waif waxes apace. 

 As soon as capable of independent movement, the tiny fish, scarce 

 half an inch long, with its yolk sac as yet unabsorbed, strikes out 

 for the deeper portions of the river, its instinct possibly teaching 

 it that to tarry is destruction, for there it would become the as- 

 sured prey of the minnows, killifish, and other small fry that 



