Observations upon the Nervous Systems of Pelagic Tunicates

The sensory and motor systems of the pelagic tunicates Doliolum, Salpa, and Thalia are described, chiefly from observations made upon the living animals by phase-contrast microscopy. These observations confirm and extend previous work, showing that the sensory systems of these animals are anatomically highly specialized. Details of the sensory cells are shown from living specimens. It is shown that the motor systems of Doliolum and the salps are essentially similar, but that of Doliolum is less specialized. The condition of the visceral nervous system in these animals is discussed, and it is concluded that the salps possess peripheral nerve-cells upon the viscera; illustrations are given of these cells from fixed specimens.