RHYTHMIC PULSATION 



309 



all measured at one time. Because of their bulk the specimens 

 of Stichopus had to be studied separately, often at intervals of 

 some days, so that various factors, including temperature differ- 

 ences, probably entered, tending to lack of uniformity in the 

 results. 



Relation between size and pulsation-rate 



, i_=Sifc. 



8 C/V. 



Fig. 8 Holothuria captiva. Temp. = 260' 



50 C/v. 



Length 



Fig. 9 Stichopus mobii. Temp. = 24°- 26° 



