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W. J. CROZIER 



13 



Fig., 13 Cross-section of a cloacal piece, showing the sunken condition of the 

 inter-radii. 



Fig. 14 Sketch of a pulsating piece, from above (X y%). 



tbrl., one of the characteristic wart-like tubercles. 



tbrl.', the delicate tactile papillae which they bear (not noted by previous 

 writers). 



movements of the anal sphincter was measured at intervals of 

 time subsequent to the isolation of the pieces. Exhaustion 

 curves obtained in this way are illustrated by figure 15. A typi- 

 cal example is given in detail : 



Experiment 83. S. June 21. Stichopus moebii; 24 cms. long; normal 

 pulsation, 58 seconds for 10 movements. Temperature varied between 

 26° and 24°C. 



There were in general two modes of exhaustion; one, a rapid 

 type (marked 'A' in fig. 15), the other showing a sort of 'fatigue 

 level.' The first type of exhaustion was exhibited by pieces of 



