Various observations by M. Fedele on the mechanism of forward and reverse locomotion, on the neurogenic origin of the locomotor rhythm and on the coordinated behavior of salp chains are confirmed or extended. Salpa fusiformis was the species chiefly studied. 2. The striated muscle fibers of the body wall exhibit nonpropagative, graded responsivity. The fibers are multiply-innervated. Adjacent fibers are not electrically coupled. 3. Intracellular recordings are reported from a pacemaker and presumed motor neurons in the brain. The locomotor rhythm is exhibited by deafferented and isolated brains. In the intact animal, sensory input can modify the rhythm and alter the firing sequence of the muscles. The rhythm is accelerated by reduction, and inhibited by elevation of the ambient light intensity. 4. The outer skin is a conducting epithelium. The cells conduct action potentials at ca. 17 cm/sec and are connected by gap junctions. Three other independently conducting inner epithelial territories are described. Propagated impulses in the excitable epithelia are believed to enter the nervous system via neurosensory processes in the skin, extending the effective fields of these receptors. 5. Salp chains show coordinated responses but, except in their earliest developmental stages, impulses are probably not through-conducted along the chain, but are relayed from one zooid to the next by an unknown mechanism. 6. Comparisons are drawn between salps and other pelagic tunicates where conducting epithelia have previously been reported.
摘要
M. 费代莱关于向前和向后运动机制、运动节律的神经源性起源以及樽海鞘链协调行为的各种观察结果得到了证实或扩展。主要研究的物种是梭形樽海鞘。2. 体壁的横纹肌纤维表现出非传播性的分级反应性。这些纤维接受多重神经支配。相邻纤维之间没有电耦合。3. 报告了从脑内的一个起搏器和假定的运动神经元进行的细胞内记录。去传入神经和分离的脑表现出运动节律。在完整动物中，感觉输入可以改变节律并改变肌肉的放电顺序。节律会因环境光强度降低而加快，因环境光强度升高而受到抑制。4. 外皮是一种传导上皮。细胞以约17厘米/秒的速度传导动作电位，并通过间隙连接相连。还描述了另外三个独立传导的内上皮区域。可兴奋上皮中的传播冲动被认为通过皮肤中的神经感觉过程进入神经系统，从而扩展了这些感受器的有效作用域。5. 樽海鞘链表现出协调反应，但除了在其最早的发育阶段外，冲动可能不会沿着链直接传导，而是通过一种未知机制从一个个体传递到下一个个体。6. 对樽海鞘与其他先前已报道有传导上皮的远洋被囊动物进行了比较。
