diff --git a/history/005_letter_test/src/main/java/com/github/drinkjava2/frog/egg/Egg.java b/history/005_letter_test/src/main/java/com/github/drinkjava2/frog/egg/Egg.java
new file mode 100644
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--- /dev/null
+++ b/history/005_letter_test/src/main/java/com/github/drinkjava2/frog/egg/Egg.java
@@ -0,0 +1,83 @@
+/*
+ * 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.egg;
+
+import java.io.Serializable;
+import java.util.ArrayList;
+import java.util.List;
+
+import com.github.drinkjava2.frog.Frog;
+import com.github.drinkjava2.frog.brain.Organ;
+import com.github.drinkjava2.frog.brain.organ.Ear;
+import com.github.drinkjava2.frog.brain.organ.Eye;
+import com.github.drinkjava2.frog.brain.organ.MoveJelly;
+import com.github.drinkjava2.frog.util.RandomUtils;
+
+/**
+ * Egg is the static structure description of frog, can save as file, to build a
+ * frog, first need build a egg.<br/>
+ * 
+ * 蛋存在的目的是为了以最小的字节数串行化存储Frog,它是Frog的生成算法描述，而不是Frog本身，这样一来Frog就不能"永生"了，因为每一个egg都不等同于
+ * 它的母体， 而且每一次测试，大部分条件反射的建立都必须从头开始训练，类似于人类，无论人类社会有多聪明， 婴儿始终是一张白纸，需要花大量的时间从头学习。
+ * 
+ * @author Yong Zhu
+ * @since 1.0
+ */
+public class Egg implements Serializable {
+	private static final long serialVersionUID = 1L;
+
+	public List<Organ> organs = new ArrayList<>();// NOSONAR
+
+	public Egg() {// 无中生有，创建一个蛋，先有蛋，后有蛙
+		organs.add(new MoveJelly()); // MoveJelly即移动光子，也是果冻记忆细胞，本来可以分成两个器官的，图省事
+		organs.add(new Eye()); // 眼是手工创建的，必有
+		organs.add(new Ear()); // 耳是手工创建的，这个是用来测试ABCD字母识别的
+	}
+
+	/** Create egg from frog */
+	public Egg(Frog frog) { // 青蛙下蛋，每个青蛙的器官会创建自已的副本或变异，可以是0或多个
+		for (Organ organ : frog.organs)
+			for (Organ newOrgan : organ.vary(frog))
+				organs.add(newOrgan);
+	}
+
+	/**
+	 * Create a egg by join 2 eggs, x+y=zygote 模拟X、Y 染色体合并，两个蛋生成一个新的蛋，
+	 * X有可能从Y里的相同位置借一个器官
+	 */
+	public Egg(Egg x, Egg y) {
+		for (Organ organ : x.organs) {
+			if (!organ.allowVary || organ.fat != 0 || RandomUtils.percent(70)) // 如果器官没用到,fat为0，增加丢弃它的机率
+				organs.add(organ);
+		}
+		// x里原来的organ
+		if (RandomUtils.percent(70)) // 70%的情况下不作为, x就是受精卵
+			return;
+		// 从y里借一个organ，替换掉原来位置的organ，相当于DNA级别的片段切换，它要求一个随机位置的Organ都允许替换allowBorrow
+		// int yOrganSize = y.organs.size();
+		// if (yOrganSize > 0) {
+		// int i = RandomUtils.nextInt(yOrganSize);
+		// Organ o = y.organs.get(i);
+		// if (o.allowBorrow) {
+		// if (organs.size() > i && organs.get(i).allowBorrow)
+		// organs.set(i, o);// 用y里的organ替换掉x里的organ,模拟受精
+		// }
+		// }
+		// if (RandomUtils.percent(50))// 有50%的机率随机会产生新的器官
+		// organs.add(Organ.randomCuboidOrgan());
+		if (RandomUtils.percent(organs.size())) {// 器官会随机丢失，并且机率与器官数量成正比,防止器官无限增长
+			int i = RandomUtils.nextInt(organs.size());
+			if (organs.get(i).allowBorrow)
+				organs.remove(i);
+		}
+	}
+
+}