FOOD AND FEEDING IN FRESH-WATER MUSSELS. 
465 
forms of a nature similar to these mentioned. Three other specimens were kept in 
similar cultures with about the same results; the mussels took anything present small 
enough to enter the mouth. 
A culture was made up containing a quantity of red Euglenas and Microcystis, 
which are green in color. Four mussels, ranging from 18 to 25 millimeters long, were 
kept in this for a time — about 24 hours in most cases. Examination showed that the 
mussels took some of everything small enough to enter the mouth, including sand 
and debris. To cite one case in detail, the alimentary canal could be traced from 
the stomach to the anus by the red color due to the red Euglenas. Upon teasing this 
red mass apart clumps of the green Microcystis could be found in it. Numbers of 
other forms and material of different sorts were also found, as sand, earth, loricas of 
rotifers, the test of a Cladoceran, bits of algae, and part of the test of a Diffiugia. 
Upon examining the masses in the intestine it appeared as if the coloring matter 
from the Euglenas was in the form of a liquid, or assumed that form when the Eugle- 
nas disintegrated. Many of the loricas of the rotifers, the test of the Cladoceran, and 
the spaces in the disintegrating algae previously occupied by chromatophores were 
filled with what appeared to be lakes of pink or orange-red color. Some of the mucus 
mingled with the material in the intestine was stained pink. It seemed evident that 
the coloring was in liquid form, or took that form when the Euglenas disintegrated 
and spread throughout the mass, collecting in almost any empty space and staining 
many of the materials a pink or orange-red color. Evidently the red Euglenas 
were being digested. 
BROKEN FILAMENTOUS MATERIAL. 
Since the water of the ponds supplying the rearing troughs contained much 
debris from the disintegration of algae and filamentous diatoms, it seemed of interest 
t-o use such material in direct feeding experiments upon juvenile mussels. Some 
of the alga (Edogonium was ground up in a mortar and put in tap water to form a 
culture in which several mussels were kept, most of them some 10 or 12 hours. 
The intestine was then examined with the following results: 
Lampsilis luteola, 10 mm. long. Two pieces were found that were unmis- 
takably portions of (Edogonium, one being a complete cell. There was also a 
general mass of fine debris that appeared to be largely made up of fragments of the 
cell wall and pyrenoid bodies from (Edogonium. 
L. fallaciosa, 12 mm. long. One almost entire cell and a recognizable portion 
of another; a general mass of fragments as in the preceding case. Five other mussels 
were used in the same experiment with practically the same results. 
Further proof that fragments of aquatic forms of various sorts are ingested is 
furnished by observations made upon some specimens of L. luteola taken from a 
certain trough in which the water contained a great abundance of empty loricas of 
Dinobryon. Quantities of these loricas were found in the alimentary canal of 
these mussels, sometimes as many as 20 being still uni ted in one fragment, as 
recorded on page 461. 
