382 W. J. CROZIER 



article. In the pigmented oesophagus hes the region at which 

 the anterior connections of the gut are ruptured in the process of 

 visceral autotomy. The oesophagus leads into the stomach, 

 which occupies the remainder of the first (^dorsal') loop of the 

 gut, passing posteriorly into the reflexed intestine. The intestine 

 itself is white, and of uniform diameter throughout its length down 

 to the sphincter constriction at the point of entrance into the 

 cloaca. The stomach, two or three times the diameter of the 

 intestine, contains yellowish or orange digestive fluid, and by 

 peristaltic movements mixes this fluid with the ingested mud. 

 The material which is passed on into the intestine is there com- 

 pacted and for several hours undergoes a process of segmentation 

 before being voided in a more or less continuous mass. 



The total length of the gut increases rapidly with the size of 

 the Stichopus (figure 2), and the maximal capacity is less than 

 proportional to the cube of this length (figure 1, B). The length 

 of the alimentary tract was estimated in a number of 'full' indi- 

 viduals, as the intestine is very quickly shortened by contraction 

 when cut from 'empty' specimens. The direct proportionality 

 between gut-length and length of individual (figure 2) seems to 

 show that the judgment based on the 'full' condition (employed 

 in the construction of figure 1, A,) was sufficiently accurate. The 

 fatt that the stomach is never entirely filled with sand, but al- 

 ways contains a fair volume of digestive juices, probably accounts 

 for the deviation from expectation regarding the relation between 

 length and gut-capacity (figure 1, B,); as it is, the ratio — (dry 

 weight of maximal contents) : (cube of the length of gut) — de- 

 creases with increasing length of animal. 



These determinations show that when filled to its maximum the 

 gut of an average Stichopus of ordinary length (27 cms.) contains 

 about 46 gms. (dry weight) of bottom material; this is mainly 

 composed of calcareous fragments of various kinds. If it 'ate' 

 but once in the twenty-four hours, such an individual would pass 

 through its intestine, and deposit in the form of castings, some- 

 thing like 1.4 kilos (dry weight) of bottom material in one month, 

 at this time of year (November). This estimate is, as a matter of 

 fact, much too low. 



