322 W. J. CROZIER 



minutes. These effects were secured in solutions 6i the fol- 

 lowing composition: 



1) 95 cc. sea water + 5 ce. t^ sodium citrate. Cloacae with the 

 radiating muscles cut pulsated for about fifteen minutes, but irregu- 

 larly; parts of the anal sphincter closed before others, so that the anus 

 presented a ragged outline. 



2) Van't Hoff solution without Ca. Effect the same as in (1), but 

 less marked. In both solutions isolated sphincters pulsated for several 

 minutes. 



3) f^r NaCl. Cloacal ends with the radiating muscles cut pulsated 

 slowly, but the sphincter did not open at all. 



4) 100 cc. -M, NaCl + 2 cc. ^ NH4OH. Slow pulsations, with in- 

 complete closure of the anus. 



In none of these tests did the pulsation last for more than a 

 few minutes. These experiments are not, of course, decisive 

 as regards an answer to the question of the relation of Ca to 

 pulsation. Continuous stimulation resulting from the action of 

 an exciting solution upon ectodermal sense organs, or upon 

 muscles, might, in connection with the refractory period, produce 

 the same result. 



The integumentary nerve-net does not play a necessary part 

 in the transmission of the wave of pulsation, since cloacal pieces 

 having the integument cut in various ways (figs. 17 and 18) 

 pulsated with complete coordination after some preliminary re- 

 adjustment following the disturbances of the operation. To 

 give an example: 



Experimeyit 84-2- July 22, 3.44 p.m. a cloacal piece, pulsating in 

 sea water at the rate of 105 seconds for 10 pulsations, was cut as shown 

 in figure 18, so that two separate rings of the integument were each 

 connected with corresponding parts of the cloaca by the radiating 

 muscles. 



3.52 Posterior part pulsating feebly. 



3.57 Both parts beating. Pulsations of normal amplitude; rate, 96.9 seconds 

 for 10 movements. 



4.10 103.9 seconds for 10 movements. 

 4.30 115 seconds for 10 movements. 

 8.45 Pulsating in irregular fashion. 



The cloaca itself is therefore able to control the coordination of 

 the pulsating system. 



