326 



EDWARD C. DAY 



h. Rhythmical contractions occurred every minute or two in- 

 volving local portions of the oral margin. These periodic con- 

 tractions are shown by the series of diagrams in figure 5. The 

 letters D and P indicate the distal and proximal ends, re- 

 spectively. The arrows indicate the points at which contraction 

 occurred. 



No. Tr 



1. 4-ir-io& 4S-':00"U 1^. 



2. 50:I5\J 46: /y Xj ,^ 



3. 5l:ZoU 48:00 (J lb. 



4. 35:00 CJ 48:30 C//7. 



5. 2>l:l0U 5-0:00 U /3. 



6. 5i>:Qoij^ SO: 10 \j 79. 

 7 37:50 U ^/:35 U 

 & 38:00 C/ S:Sf.Ooty' 



38:30 U 5-4:30^0 



II. 42:00L/ 55:50 & 



9 



JO. 40:10 



11 43:00 u 

 II 44-oo'U 



^ ^£3- 



20. 

 11. 



21. 

 Z5. 



Z5. 



Fig. 4 Three Cionae intestinalis operated on as indicated by the dotted 

 lines. The nerve ganglion is represented by the black spot at the crotch of the 

 siphons. In animal No. 9 the ganglion was amputated along with the incurrent 

 siphon. 



Fig. 5 A series of diagrams showing automatic rhythmical contractions in 

 an amputated incurrent siphon of Ciona intestinalis (8A of Fig. 4). These 

 occurred every minute, more or less, as will be seen from time recorded in minutes 

 and seconds to the left of each figure. The distal end of the siphon is uppermost 

 in all figures except No. 25. D distal; F proximal. Arrows indicate the points 

 and direction of contraction (puckering in, curling out or pursing). The 

 asterisk means a stimulus applied at that point. 



