NERVOUS SYSTEM OF THE TUNICATE 323 



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Operations. A few amputations and incisions were tried on 

 Ascidia atra, but the animals did not live more than a day or 

 two after the operations, due apparently to adverse laboratory 

 conditions: owing to the presence of iron rust in the laboratory 

 water, it was impossible to keep the tunicates alive for more 

 than four or five days. No experiments were tried on ampu- 

 tated siphons. An animal, however, from which the ganglion 

 had been excised, recovered and displayed irritability of both 

 siphons to tactile stimulation. As the animal died shortly after, 

 no regeneration had time to occur. 



Light reactions. Both oral and aboral siphons of Ascidiaatra 

 were tested for sensitivity to sunlight, but no evidence of a 

 positive nature was obtained. When the animals lay in jars of 

 running sea-water and kept in semidarkness, they closed the 

 siphons periodically at approximately one-minute intervals, and 

 when sunlight was focused on the siphon it could not be found 

 to have any effect on these contraction-intervals. 



EXPERIMENTS ON CIONA INTESTINALIS 



For sake of comparison, a few operative experiments were 

 performed on Ciona in which the siphons were amputated at 

 various levels and records of reactions made for both amputated 

 pieces and the bodies. The results are given in protocol 5 

 below, and by diagrams in fig. 5. 



1. Effect of operative experiments on Ciona intestinalis, 

 Animals 7, 8 and 9. 



April 17, 1913. Three specimens of Ciona intestinalis were 

 operated upon, after first narcotizing with cocain, by amputating 

 the siphons as indicated by the dotted lines in figure 4. It will 

 be noted that in the operation on animal 9 the nerve ganglion 

 (black spot at the crotch) was included in the amputated piece. 



From the protocol it will be noted that: 



a. Ten minutes after the operation all the amputated pieces 

 except 7 B were unresponsive to stimulation; the amputated 

 excurrent siphon 7 B showed automatic rhythmical contractions. 



