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THE AMERICAN XATURALIST [Vol. XLI 



croft that the ectodermal ampiillse in the test substance of the 

 Botrvlhis colony are rhythmically contractile and have a regular 

 circulatory office. There is coordinated activity among large 

 numbers of ampulla? in the same colony and this seems to be 

 without the intermediation of the nervous system. 



The unique form of tunicate heart action has continued to 

 attract attention. The most comprehensive study of it is by L. 

 Schultze on Salpa. "The heart of Salpa is an example of purely 

 muscular self-regulation in a highly coordinated mechanism of 

 motion." This sentence summarizes Schultze's positive results. 

 Neither cerebral influence nor blood pressure play a causal })art 

 in the phenomena. Of similar general import Bancroft and 

 Esterly find proof of polarization through its own activity in the 

 heart of Ciona. On the other hand ]\Iagnus, Hunter and Froh- 

 lich bring forward rather strong evidence of the dependence of 

 heart action in Ciona on ganglia and to some extent on the brain. 



