BOTTOM MATERIAL INGESTED — -HOLOTHURIANS 



381 



A, shows the relation obtained between the length of a Stichopus 

 and what may be called the maximal, or 'full/ intestinal capacity. 

 The errors involved in weighing the contained mud are probably 

 no greater than those incidental to the measurement of the length 

 of a Stichopus. The intestine in the instances considered 'full' 

 was tightly packed with sand, as was also the oesophagus and 

 buccal chamber. In the region of the stomach proper, at least 

 in its anterior half, the material was less closely compacted. 



cms. 



— 130 



110 



o 



(0 



+» 



J* 



(0 



c 



-i90j 



00 

 0) 



— 70 



50 



10 20 30 40 50 60 70 gmS. 



Weight of Intestinal Contents 



Fig. 1 A (scale to the left) — relation between length of Stichopus and the 

 average weight of the washed, air dried, contents of the 'full' alimentary tract. 

 B (scale to the right) — Same for the length of the intestine (from figure 2). 



The several regions of the alimentary tract of Stichopus, it may be 

 mentioned incidentally, are more sharply delimited than text- 

 book descriptions of holothurian anatomy would lead one to sup- 

 pose. The short white buccal chamber is followed by a very 

 thin-walled, highly contractile, oesophagus, which is more or less 

 heavily pigmented by a substance belonging to the ' echinochrome' 

 or 'antedonin' group. This oesophagus appears to exert a 

 suctorial function; but the activities of the different segments of 

 the alimentary tract may be better considered in a subsequent 



