FOOD AND FEEDING IN FRESH-WATER MUSSELS. 463 
Quadrula undata — 22 hours. A little carmine in the intestine; the style was 
faintly pink. 
Lampsilis gracilis — 3 hours. Considerable carmine in the intestine. 
A specimen of Lampsilis luteola, 3 mm. long, was kept for a time in a carmine 
suspension and then sectioned. Particles of carmine were found in the stomach, 
and the intestine was packed full. A photomicrograph of a section is shown in 
Figure 7 (opp. p. 455). 
Several large or adult mussels were tried in similar suspensions. The results 
follow. 
Plagiola donaciformis — 4 hours. No carmine. 
Lampsilis ventricosa — 5 hours. No carmine. 
Sphserium sp. — -2 specimens. Much carmine in the intestine. 
Lampsilis anodontoides — 22 hours. No carmine. 
Quadrula plicata — 22 hours. No carmine. 
Quadrula undata — 18 hours. No carmine. 
Obovaria ellipsis — 19 hours. No carmine. 
Obliguaria rejlexa — 19 hours. Carmine in stomach and rectum. This indi- 
vidual was 1| inches long, an adult being somewhat over 2 inches in length. 
Lampsilis Isevissima — 27 hours. No carmine. 
Lampsilis Isevissima — 27 hours. 3 or 4 small particles of carmine found in the 
rectum. 
Lampsilis gracilis — 22 hours. No carmine. 
The results are summarized in the following table: 
Table 1. — Showing results of test in borax carmine suspension. 
Ingested carmine. 
Did not ingest carmine. 
Small (25 mm. or less) . 
Adult. 
Small (25 mm. or less). 
Adult. 
Lampsilis gracilis, 4 speci- 
mens. 
L. Isevissima, 3 specimens 
L. fallaciosa, 1 specimen 
Obovaria ellipsis, 1 specimen __ 
Sphaerium, over half a dozen.. 
Obliquaria reflexa, 1 specimen. 
Obovaria ellipsis, 4 specimens. 
Plagiola donaciformis, 1 speci- 
men. 
Lampsilis ventricosa, 1 speci- 
Lampsilis Isevissima, 1 speci- 
men, a few particles only. 
men. 
L. anodontoides, 1 specimen. 
Quadrula plicata, 1 specimen. 
Q. undata, 1 specimen. 
Obovaria ellipsis, 1 specimen. 
Lampsilis gracilis, 1 specimen. 
Quadrula pustulata, 1 speci- 
men. 
Q. undata, 1 specimen. 
Q. pustulosa, 1 specimen 
Anodonta corpulenta, 1 speci- 
It will be noted that none of the adult mussels except the Sphaeriums, the 0. 
rejlexa, and the L. Isevissima ingested carmine, and that only one of the juveniles, 
0. ellipsis, failed to take any. Except in the cases of 0. ellipsis, L. gracilis, and 
0. undata, the adults were of different species than the juveniles. The fact that car- 
mine was not taken by them may be a question of a species difference and not one of 
age. From the fact, however, that in three cases it was an age difference, it would 
seem that the preponderance of evidence is in favor of the theory that as the mus- 
sels approach the adult stages they take less carmine. This would, no doubt, account 
for the differences between our results and those of Allen. From the observations 
