几千几万年过去了，这些动物在水里游起来比在陆地上行走更加悠然自得；几百万年以后，它们便压根儿不需要腿了，这时就可辨认出它们是鲸了。它们的前腿变成鳍状肢，今天的鲸鱼便是用它来掌握方向的；它们的后腿萎缩了，因而只有当鲸鱼被解剖时，才能在皮肤下见到后腿的一些痕迹。
The Badger，a Courageous Fighter
The badger has been nicknamed“doormat”because of its broad，squat form and its hairy back．Actually it is a courageous fighter．In pioneer days it was considered great sport to turn a pack of dogs loose on this furry foe，but few dogs were willing to challenge the badger a second time．
When attacked，the badger digs a protective hole；if cornered，it releases a strong odor from glands near its tail．The badger’s height—only about nine inches—places its throat below the line of attack of most dogs，and the back of its neck is protected by coarse hair．
In a fight，the badger’s front claws are for mid able weapons．It can leave a dog limping after one wellplaced bite of its sharp teeth．Only the lowslung dachshund can easily get a deadly throat hold on the badger；this dog was once much used in“badgering”．Fortunately for the badger，the popularity of this sport has decreased considerably．
獾——勇猛的斗士
獾，因其宽宽的、矮墩墩的形体和毛茸茸的背部一直被人们浑称为“门垫”。实际上，它是一名勇猛的斗士。在拓荒者年代，放出一群狗与这个有毛皮的对手相斗被认为是极精彩的娱乐。然而，极少有狗愿意向獾作第二次挑战。
獾在受到进攻时，便刨一个洞藏身；在它走投无路时，就从靠近尾部的腺体释放出一种浓烈的气味。獾的高度——仅9英寸左右，使其喉管处于大多数狗的进攻线以下，它的颈背有粗糙的毛保护着。
在搏斗中，獾的前爪是锐不可当的武器。獾瞄准了狗的腿部，用利齿咬上一口便可使它成为跛足。只有形体矮小的猎獾狗，能轻而易举地咬住它的喉管而致它于死地。这种狗曾广泛用于“狗撩獾”运动中。对獾说来，幸运的是，这项运动的风靡程度已大大下降了。
A Species of Black Spider on
the Slopes of Mount Qomolangma
Man has become master of the earth’s surface．He is constantly probing into the earth’s depths and into the atmosphere’s upper reaches．Yet it is doubtful whether man，with all of his intelligence and vigor，holds his planetary seat with greater assurance than a vast tribe of small，manylegged animals that pass their lives at his feet—the spiders．
Spiders are among the marvels of science．They dwell at higher altitudes than any other creature their size or larger．On the slopes of Mount Everest，at an altitude of twentytwo thousand feet—five thousand feet above the vegetation line—lives a species of black spider only a quarter of an inch long．This is an incredible environment for creatures so delicately constructed．To protect themselves from the chill of night，they take shelter in crevices where the twentyfourhour variation in temperature is only twelve degrees，as against fortyfour on the outside．
Spiders inhabit other unlikely placesrabbit burrows，flowers，ant hills，and the desolate，drafty aeries of eagles．They have been found soaring through the air five miles above the earth．One species has been discovered in an African cavern more than two thousand feet underground．
珠穆朗玛峰山坡上的黑蜘蛛
人类已经成了地球表面的主人。人们总是不断地探索地球的深层和大气层的上层区域。然而，人类能否凭借一切智慧和精力，比一大批在其脚下生活的多腿动物——蜘蛛——更有把握地保持其地球上的席位，却还是令人怀疑的。
从科学角度来看，蜘蛛是奇特的，它们比体形与其相当或大于它们的任何别的动物栖息的地方要高。在植被线以上5000英尺至2.2万英尺的珠穆朗玛峰山坡上，生活着一种仅1／4英寸长的黑蜘蛛。对于形体这样柔弱的动物，能生存在这种环境是让人难以置信的。夜晚，为了避免受寒，它们在罅隙中栖身。那儿24小时内的温差仅有12度，而外面的温差则达44度。
蜘蛛还住在人们意想不到的其他地方——兔窟、花朵、蚁冢和荒凉通风的鹰巢。人们还发现它们升腾于地球上空5英里的高处。在地下2000英尺的非洲一座大洞穴中，也发现了一种蜘蛛。
The Fiddler Crab，a Living Clock
The fiddler crab is a living clock．It indicates the time of day by the color of its skin，which is dark by day and pale by night．The crab’s changing skin color follows a regular twentyfour hour cycle that exactly matches the daily rhythm of the sun．