diff --git a/history/003a_legs/src/main/java/com/github/drinkjava2/frog/brain/organ/FootPosFeel.java b/history/003a_legs/src/main/java/com/github/drinkjava2/frog/brain/organ/FootPosFeel.java
new file mode 100644
index 0000000..74d48b4
--- /dev/null
+++ b/history/003a_legs/src/main/java/com/github/drinkjava2/frog/brain/organ/FootPosFeel.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright 2018 the original author or authors. 
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by
+ * applicable law or agreed to in writing, software distributed under the
+ * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS
+ * OF ANY KIND, either express or implied. See the License for the specific
+ * language governing permissions and limitations under the License.
+ */
+package com.github.drinkjava2.frog.brain.organ;
+
+import com.github.drinkjava2.frog.Frog;
+import com.github.drinkjava2.frog.brain.BrainPicture;
+import com.github.drinkjava2.frog.brain.Organ;
+
+/**
+ * Move down frog 1 unit if outputs of nerve cells active in this zone
+ */
+public class FootPosFeel extends Organ {
+	public static final int BFOOTPOSSTART_X = 70;
+	public static final int RFOOTPOSSTART_X = 570;
+	private static final long serialVersionUID = 1L;
+
+	@Override
+	public void drawOnBrainPicture(Frog f, BrainPicture pic) {// 把自已这个器官在脑图上显示出来
+		super.drawOnBrainPicture(f, pic);
+		if (x < 500) { // x小于700的器官是底脚的
+			int pos = Math.round((x - BFOOTPOSSTART_X) / 30) - 5;
+			if (f.bFootPos == pos)
+				pic.fillZone(this);
+		} else {// 否则就是右脚
+			int pos = Math.round((x - RFOOTPOSSTART_X) / 30) - 5;
+			if (f.rFootPos == pos)
+				pic.fillZone(this);
+		}
+	}
+
+	@Override
+	public void active(Frog f) {
+		if (x < 500) {
+			int pos = Math.round((x - BFOOTPOSSTART_X) / 30) - 5;
+			if (f.bFootPos == pos)
+				activeOtherCells(f);
+		} else {
+			int pos = Math.round((x - RFOOTPOSSTART_X) / 30) - 5;
+			if (f.rFootPos == pos)
+				activeOtherCells(f);
+		}
+	}
+
+}