BOTTOM MATERIAL INGESTED — HOLOTHURIANS 389 



even though they do not devour corals as Darwin at first believed 

 from the reports made to him and from the supposed masticatory 

 function of the stone-ring. 



SUMMARY 



1. A preliminary estimation has been made of the amount of 

 bottom material (mainly calcareous) deposited in littoral situ- 

 ations about the Bermuda Islands which may be passed through 

 the intestine of the large holothurian, Stichopus moebii Semper. 



2. This estimate is based upon the fact that it is possible to 

 obtain a fairly accurate idea of the rate of feeding in Stichopus, 

 and of the maximal contents of the gut in individuals of different 

 sizes. 



3. In certain typical areas frequented by this species the 

 amount of bottom material passing through the intestine of 

 Stichopus is roughly 6 to 7 kilos (dry weight) per square meter 

 per year. 



4. It is estimated that in the enclosed sink Harrington Sound 

 the amount of bottom deposit annually eaten by Stichopus is 

 perhaps 500 to 1000 tons. 



5. The fluid stomach contents of Stichopus are sufficiently 

 acid to dissolve some calcium carbonate. The mutual attritionof 

 particles in the intestine is probably of small significance for the 

 formation of finely divided particles.^ 



Pembroke, Bermuda, January 5, 1918. 



2 Some of the observations recorded in this paper were made with the aid of 

 apparatus purchased by means of a grant to the Director of the Bermuda Bio- 

 logical Station from the C. M. Warren Fund of the American Academy of Arts 

 and Sciences, to aid in certain investigations of seawater and the chemical com- 

 position of body fluids of marine animals. 



