Ward S
Proc Natl Acad Sci U S A. 1973 Mar;70(3):817-21. doi: 10.1073/pnas.70.3.817.
The nematode Caenorhabditis elegans is attracted by at least four classes of attractants: by cyclic nucleotides, cAMP and cGMP; by anions, Cl(-), Br(-), I(-); by cations, Na(+), Li(+), K(+), Mg(+); and by alkaline pH values. The nematode's behavioral response to gradients of these attractants involves orientation and movement up the gradient, accumulation, and then habitutation. Comparison of the tracks of wild-type and mutant animals responding to gradients of attractants indicates that sensory receptors in the head alone mediate the orientation response and that the direction of orientation is determined by the lateral motion of the head. Therefore, the orientation response is a klinotaxis.
环核苷酸，即环磷酸腺苷（cAMP）和环磷酸鸟苷（cGMP）；阴离子，如氯离子（Cl⁻）、溴离子（Br⁻）、碘离子（I⁻）；阳离子，如钠离子（Na⁺）、锂离子（Li⁺）、钾离子（K⁺）、镁离子（Mg⁺）；以及碱性pH值。线虫对这些引诱剂梯度的行为反应包括定向并沿梯度向上移动、聚集，然后产生习惯化。对野生型和突变型动物对引诱剂梯度反应轨迹的比较表明，仅头部的感觉受体介导定向反应，并且定向方向由头部的侧向运动决定。因此，定向反应是一种趋性运动。
