332 



W. J. CROZIER 



In all cases of anaesthetisation the quiescent condition showed 

 the anal sphincter in diastole and the cloaca itself more or less 

 closed, that is, with the radiating muscles relaxed. 



Traces of anaesthetics commonly induce a temporary acceler- 

 ation in the rate of rhythmic movements. This is also the case 

 with the cloaca of Stichopus (fig. 25). The effect on pulsation 

 rate was less evident than the concomitant increase in ampli- 

 tude and vigor of contraction. The effect lasted only a few 

 minutes. 



TABLE 8 

 Volume of solution in each case = 250 cc. 



b) Alkaloids. The influence of depressing alkaloids was also 

 studied ; in each instance the history of five individual isolated 

 cloacal ends being followed in detail and the general result 

 checked by less detailed observations upon other pieces. The 

 results with regard to pulsation and irritability to mechanical 

 stimulation are summarised in table 8. Representative indi- 

 vidual curves of exhaustion in these solutions are plotted in 

 figure 26. 



The powerful effects of nicotine and atropine are comparable 

 to their influence on many other types of smooth muscle. 



