180 



SCIENCE 



[N. S. Vol. XLIV. No. 1127 



ism is non-reversible, hence his conclusion in 

 this case that the oysters starved in the pres- 

 ence of an abundant supply of food. Although 

 starving, the oysters were powerless to prevent 

 the rejection of food material for the remark- 

 able reason that the food material was reach- 

 ing their feeding mechanism in embarrassing 

 abundance. 



It was not contended that the sediment was 

 distasteful, for, in the organization of an ani- 

 mal with such a purely automatic feeding 

 mechanism, what possible place could be found 

 for so useless a thing as a sense of taste? 



To test the validity of this contention the 

 following experiments were carried out on the 

 oyster beds where the oysters were said to 

 have died from starvation, at a time when the 

 waters were roiled and turbid from the opera- 

 tions of nearby dredges. 



A considerable number of oysters of uniform 

 size were first gathered from a bed far re- 

 moved from the scene of the dredging opera- 

 tions. Five of them were immediately opened, 

 their stomach contents removed and preserved 

 in a vial for future study and analysis. The 

 remaining oysters were thoroughly cleansed of 

 all foreign material and stored for three days 

 in a cool damp place. Twice each day they 

 were placed for an hour in filtered sea water in 

 order that they might expel from their shells 

 the aecumuated excreta. They were allowed 

 to take no food. At the end of the third day of 

 fasting, the primary object of which was to 

 remove from the alimentary canal all previ- 

 ously ingested food material, the oysters were 

 taken to a selected point on one of the oyster 

 beds over which the sediment from the dredges 

 was being carried by the rising tide and there, 

 after five of them had been opened and their 

 stomach contents removed, placed upon the 

 bottom. 



To facilitate depositing the oysters upon 

 and removing them from the bottom, they 

 were placed in a coarse-meshed wire tray to 

 which cords were attached. 



At the end of an hour from the time the 

 oysters were deposited upon the bottom in the 

 turbid water the tray was lifted for a moment, 

 the stomach contents of five of the oysters were 



removed, and the tray with the remaining 

 oysters returned to the bottom. At the end of 

 the second hour this process was repeated and 

 also at the end of the third hour. When the 

 experiment was over the unused oysters were 

 left upon the bottom in the tray for fourteen 

 days to note the effect of the sediment upon 

 them with the result that all thrived and made 

 perceptible growth of shell. 



The microscopic examination and estimate 

 of the number of food organisms in the stom- 

 ach contents taken from this series of oysters, 

 which was made according to the " Rafter 

 cell " method, resulted as follows : 

 Each oyster estimated to contain, when collected 



August 19, 10.30 a.m., 18,500 food particles. 

 Each oyster estimated to contain, after fasting till 



August 22, 1.30 p.m., 8,250 food particles. 

 Each oyster estimated to contain, after feeding 1 



hour, August 22, 2.30 p.m., 11,500 food particles. 

 Each oyster estimated to contain, after feeding 2 



hours, August 22, 3.30 P.M., 17,750 food particles. 

 Each oyster estimated to contain, after feeding 3 



hours, August 22, 4.30 p.M.,3? 



A second experiment in every way similar 

 to the first, except that the oysters were sub- 

 jected to a preliminary fast of four instead of 

 three days' duration, was carried out between 

 August 31 and September 4, 1911. The esti- 

 mates of the stomach contents of the oysters 

 used in this experiment are as follows : 

 Each oyster estimated to contain, when collected, 



August 31, 10 a.m., 12,125 food organisms. 

 Each oyster estimated to contain, after fasting till 



Sept. 4, 1 P.M., 2,850 food organisms. 

 Each oyster estimated to contain, after feeding 1 



hour, Sept. 4, 2 P.M., 10,250 food organisms. 

 Each oyster estimated to contain, after feeding 2 



hours, Sept. 4, 3 p.m., 16,500 food organisms. 



RESULTS AND CONCLUSIONS 



The results of these experiments show con- 

 clusively that oysters can and did feed actively 

 in waters that were turbid with sediment, a 

 fact that is in direct opposition to Dr. Kel- 



3 The food material removed from the stomachs 

 of the oysters which had been feeding for three 

 hours in the roiled water was so densely crowded 

 with sediment that it was impossible to make the 

 diatom counts necessary for an estimate of the 

 total number of food organisms. 



