THE GERMAN CARP IX THE UNITED STATES. 569 



the spring the Silesian carp, thoug-h apparentl)^ well nourished, had 

 reached a length of onl}^ 5 to 6 cm., while the Galician carp had grown 

 to a length of IS cm. The author answers the question. Wherein, 

 under natural conditions, rests the ability for cjuick growth in fresh 

 water fishes? by saying: "Partly, perhaps, in a better assimilation of 

 the food, but mostly upon a better selection of the same. The richer 

 this is in nitrogen, the greater, within certain limits, is its nutritive 

 effect." (Zoologische Garten, Jahrgang 37, 1896, p. 845, 346.) « 



In order to determine the nature of the principal food of the carp 

 in this countr}^ I have examined the alimentary tracts of a great many 

 individuals. Many of these examinations were not made in detail, 

 but only to determine the presence or absence of certain things, such 

 as the eggs of other fishes. A list of the contents of stomachs and 

 intestines of 33 carp, however, is given below. These examinations 

 were made with more care than the rest, but are for the most part 

 only qualitative, the relative quantities of the various materials being- 

 given only in rough approximates. The carp were from several dif- 

 ferent localities and a variety of conditions. The list is given in full 

 because it is believed to be important to convey a very thorough knowl- 

 edge of the nature of the food of the carp in our waters. I have never 

 found large particles of food of an}- kind in the alimentary tract, the 

 largest being strips of vegetable epidermis perhaps an inch long, 

 wings and other portions of insects, small snail shells, and the like. 

 It is stated that carp can grind or " masticate" thin food to a certain 

 extent with the fiat, knob-like pharyngeal teeth, and prol)ably this in 

 part explains the fact that what is found in the stomach is usually so 

 much broken up. Houghton (1879, p. 17) even maintains that ""por- 

 tions of vegetable food are returned to the throat and remasticated by 

 these pharyngeal grinders," though I know of no evidence in support 

 of this hypothesis. The finely ground condition of the stomach con- 

 tents leads to some wonderment among the fishermen, who are accus- 

 tomed in other fish to find the food, such as smaller fish, swallowed 

 whole, and one man always insisted to me that carp " digest their food 

 in their heads." 



1. Specimen from St. Clair Flats, June 30, 1901. Chara, small 

 amount; May fly (ephemerid) wings and broken fragments, consid- 

 erable numbers; insect larvw, small; roots, decaying leaves, and epi- 

 dermis ("bark") of aquatic plants, large amount; small shells and 

 fragments: sand. All the Clicira seemed to be packed in the small 

 intestine. This was noticed in other cases, and seems to indicate that 

 when the fish get among the Cham, they eat a large amount of it. 



2. Specimen from St. Clair Flats, July 3, 1901. Rootlets and other 

 vegetable matter, such as would be found in bottom mud; coleopter- 



aFor a more detailed discussion of the processes of digestion and assimilation in tlie carp, the 

 reader is referred to a later paper by Knauthe (1898). 



