BULLETIN OF THE UNITED STATES FISH COMMISSION. 279 



ter, held and macerated in the conical division of the stomach, passes 

 gradually into the gizzard, where it is in time thoroughly disintegrated 

 by the powerful walls of this muscular apparatus, aided by the sharp 

 points and edges of the broken shells of the infusoria, lieduced to 

 ehyuie — the brownish uuicns of some observers — it passes the snudl 

 l)yloric orifice, is changed by admixture with the proper secretions, which 

 meet it at the threshold, and is immediately siicled up into the cceca, 

 that distend to receive it. 



In these receptacles the liquid food, prepared in the ocean, is stored 

 away to nourish the fish in its long passage, live or six hundred miles 

 perhaps, to the headwaters of rivers, where the ova are to be deposited 

 and receive impregnation. Thus we may explain how it is that a fish 

 coming to us in superb condition from the sea, with nothing apparently 

 in its intestinal canal but a little discolored mucus, can make this ascent, 

 execute the functions necessary for the reproduction of its species, and 

 descend to its feeding grounds in the deep. 



In the absence of food the fish feeds on the nutritive contents of the 

 cceca; either by forcing a certain quantity of the fluid into the large 

 intestine, or, and this is far more likely, by absorption immediately from 

 the cceca — each of these appendages being provided with a sphincter, 

 or valvular arrangement, to prevent the involuntary passage of its 

 contents into the general reservoir. The action of gravity on the free 

 extremities of the loaded tubes would materially assist this retention. 



Something like this, there is little doubt in my mind, takes place in 

 the other species, and genera, provided with cceca, that run from the sea 

 to spawn. These useful appendages varying in number, and size, ac- 

 cording to the habits of the fish, and the presence or absence of food in 

 the fresh-water streams which they ascend. 



Some finding, although precariously, appropriate food, a part of the 

 fortuitous excess of to-day is stored away for to-morrow's scarcity. 



The adult shad from its habits during the season for spawning (for the 

 fatness of the fish and the apparent emptiness of its alimentary canal 

 have long been subjects of wonder) requiring an abundant supply of food 

 for long voyages, has a great number of receptacles. 



The number varies in individuals of the same species; less than 

 seventy and more than ninety-five having been carefully counted by 

 me in the specimens examined. And this difference seems to be directly 

 in proportion to the size, and, there is good reason to believe, the age of 

 the fish. It may be thus explained. In the young adult shad some of 

 the coeca are rudimentary.* They are gradually developed with the 

 growth of the fish until a fixed number is reached for the species. 



* Since tbis paper was read before the Academy, I have found some of these organs 

 in a rudimentary state in the young adult of Labrax lineatus (striped bass, rocls-fish), 

 and in specimeus of the species of Dioplites (another of the perch family) generally 

 known as "trout" at the South. 



Preparations proving these ichthyological points are in my possession. 



