材料用具：沼虾、剪刀、光照后眼柄的提取液、灯光、暗室、光照后眼柄肌肉提取液、玻璃水槽、注射器等。
      实验步骤：
      第一步：将黑暗环境中的沼虾分成两组，分别置于光照和黑暗中，三小时后取出，先用肉眼观察体色的变化。
      第二步：证明沼虾的变色是否与眼柄有关，具体做法如下：                                                               
                                                                                                                                             。
      试验预期及结论：                                                                                                                              
                                                                                                                                              。
      第三步：若上一步证明沼虾的变色与眼柄有关，则继续证明沼虾的变化是否与眼柄中神经细胞的分泌物有关，具体做法如下：                                                                                                                         
                                                                                                                                               。　　
      试验预期及结论：                                                                                                                             
                                                                                                                                                  。