56 



HARDWICKE'S SCI ENCE- GOSSIP. 



guardianship of tender, "knife-blade" specimens 

 of finny creatures which at an early age seem to 

 assume the monotonous life of their elders, and 

 leaving them, set up for themselves. 



In spite of our many efforts we have never found 

 young Gizzard-shad less than a week old, nor could 

 we ever spy them out while yet in ovo. But they 

 are, nevertheless, an oviparous fish, the " roe" and 

 " milt " being readily found, and as easily extruded 

 as in the shad proper and herring, especially during 

 the week or more that its presence provokes the 

 wild antics of its possessor during our second 

 spring month. 



Why, we naturally ask, was this gizzard evolved, 

 which, on dissection, we find the Dorosoma has ? 

 If we looked at its food, we found tliis gizzard was 

 admirably adapted to crushing the Lymnete, 

 Tuludince, and other shelled creatures on which 

 this fish subsists mainly ; but, on the other hand, 

 we find several other fish with no such muscular 

 stomach thriving on the same food. For instance, 

 we find the yellow perch {Ferca flavescens), the Pond 

 bass {Ariibloplites pomotis), and the larger sunfish 

 {Lepomis auritus) may be seen in clear waters to 

 feed upon these same shells ; and occasionally a 

 chub i^Semotilus rJiotheus) will swallow and mash 

 one of them with its well-developed pharyngeal 

 teeth. In all these cases it will be seen that 

 strong, thickset teeth come in play to break up the 

 shell of the animal devoured ; but with this herring 

 there is no set of teeth or any bone that will crush 

 a shell ; and hence the necessity for something 

 that will. Does this "necessity" give rise to the 

 " gizzard " ? 



It may, perhaps, be asked, if this fish has not 

 suitable teeth for eating shell-bearing creatures, 

 why not feed upon something else? or, if it must 

 subsist upon the Lymnea, Puludina, and such 

 animals, why did not the persistence in so feeding 

 develop the jaws and lengthen and strengthen the 

 teeth ? One might as well ask why should the her- 

 ring not be a polyzoa feeder, and need neither teeth 

 nor gizzard ? Enough to know that the food has 

 developed a capacity to digest it, and not the 

 capacity to digest suggested the food. Tiiis is 

 shown when we compare tiie gizzard of the marine 

 fish witli that of the land-locked species. We then 

 find in the latter that the gizzard is much less 

 muscular in its walls and smaller in all its measure- 

 ments ; and the difference in the food, as found on 

 examination, shows that the marine fish's larger 

 stomach has an amount of work to do about equal 

 to the difference in the strength of the shells of 

 the marine and fresh-water species that constitute 

 the bulk of the food of this herring. 



As the muscularity of the stomach in this case 

 varies with the character of the food — the size of 

 the fishes, marine and land-locked, being the same — 

 it is logical to maintain that the food ab origine 



produced a muscular thickening at a convenient 

 point of a digestive tract, which became, by being 

 inherited, ultimately a gizzard such as the gallina- 

 ceous birds now have. We say, by being inherited; 

 for both the habit of feeding on shell-bearing 

 animals, and the anatomical advantage, as the 

 incipient gizzard may be called, would be transmit- 

 ted to the offspring, or some of them ; and if only 

 to some, then they would thrive better than their 

 fellows, for having it. 



A curious fact, in this connection, consists in the 

 habit that these fish have, of swallowing the coarser 

 grains of sand, which help to crush down the shells, 

 just as chickens swallow gravel to help to digest 

 the grains of corn that they have eaten. Purther- 

 more, on examining some marine specimens, 

 caught at sea, the gizzards also werejound to contain 

 gravel stones, but all of a larger size, seeming 

 to correspond with the increased muscularity of 

 the gizzard, and density of the shells swallowed by 

 the fish. 



One word more, and we have done. This fish at 

 sea, no doubt has it enemies ; and when land- 

 locked and free from these, it might be tliought to 

 thrive beyond calculation. Such, however, is not 

 the case. The young are greedily devoured by the 

 pilse; and the lamprey {Petromyzoii) seems to be 

 particularly partial to the adult fish. It secures an 

 attachment to the gills of the " Shad," and literally 

 worries it to death. 



THE IRISH NIGHTINGALE. 



A GENTLEMAN (for I hope it is not one of the 

 -^-*- fair sex) who signs himself)" Leprahaun," has 

 an article on the above subject in Science-Gossip 

 for September, 1872. In order to obviate the 

 necessity of constantly giving " Leprahaun " bis 

 full title, I shall curtail it to "L.," as when we Irish 

 think of leprahaun, a little man dressed in red, 

 about eighteen inches higli, seated on a three-legged 

 stool, with his legs crossed, and busily engaged 

 mending a " brogue," rises up in our imagination. 

 If you could possibly catch this little individual, 

 who may most frequently be found in quiet, out-of- 

 the-way places, your fortune would on the moment 

 be made. If you want to succeed in this feat, you 

 must not lose sight of him ; keep your eyes fixed 

 on the man and the stool. Every leprahaun has 

 charge over an immense " pot of goold ;" and if you 

 hold him fast, and watch him steadily, he will not 

 fail to show the hidden treasure. So the story goes 

 among the country people in this neighbourhood, 

 and so I learned it when a boy. 



"L." asks, " Wliat is that shy, sprightly little bird 

 which swings so curiously from yonder giant bul- 

 rush, its coal-black crest perkily raised, its throat 

 throbbing in passionate song ? " 



