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56 The Organic Foods
Are organically grown foods the best food choices? The advantages claimed
for such foods over conventionally grown and marketed food products are
now being debated. Advocates of organic foods -- a term whose meaning
varies greatly -- frequently proclaim that such products are safer and more
nutritious than others.
The growing interest of consumers in the safety and nutritional quality of
the typical North American diet is a welcome development. However, much of
this interest has been sparked by sweeping claims that the food supply is
unsafe or inadequate in meeting nutritional needs. Although most of these
claims are not supported by scientific evidence, the preponderance of
written material advancing such claims makes it difficult for the general
public to separate fact from fiction. As a result, claims that eating a
diet consisting entirely of organically grown foods prevents or cures
disease or provides other benefits to health have become widely publicized
and form the basis for folklore.
Almost daily the public is besieged by claims for "no-aging" diets, new
vitamins and other wonder foods. There are numerous unsubstantiated reports
that natural vitamins are superior to synthetic ones, that fertilized eggs
are nutritionally superior to unfertilized eggs, that untreated grains are
better than fumigated grains and the like.
One thing that most organically grown food products seem to have in common
is that they cost more than conventionally grown foods. But in many cases
consumers are misled if they believe organic foods can maintain
health and provide better nutritional quality than conventionally
grown foods. So there is real cause for concern if consumers particularly
those with limited incomes, distrust the regular food supply and buy only
expensive organic foods instead.
绿色食品绿色食品是最佳食物吗?有人认为绿色食品比通过常规方式生产和销售的食品 有更多的优越性，然而现在却有人对此提出异议。
绿色食品--这一词的用法非常不统一-- 支持者往往声称绿色食品比其它食品更安全，营养价值更高。 北美的消费者们越来越关注
他们的日常饮食是否安全和有营养。 这一发展趋势是好的。 然而这种关注多半是由一些武 断的说法引起的，即食物供应不安全或不能提供足够的营养。
尽管这些说法多数未被科学 证实，但是由于大量文章支持这一观点，使得普通群众难辨真伪。 因此那些认为只食用绿
色食品就能防治疾病或增进健康的观点便广为人知，并导致一些不科学的做法和习惯。 公
众几乎每天都被"抗衰老"食品、新型维生素以及其它具有神奇功效的食物广告所包围。 声
称天然维生素优于人造维生素，受精蛋比未受精蛋的营养价值更高，未经薰蒸消毒处理的谷 物比经过处理的好等等诸如此类的报道屡见不鲜，但没有一篇是经过证实的。
大多数绿色 食品有一共同点，即它们的价格高于以常规方式种植的食物。 但在许多情况下，如果消费
者认为绿色食品能预防疾病且营养价值高于以常规方式生产的食品，那么他们被误导了。如
果消费者们，尤其是那些收入有限的消费者们，怀疑传统食品而只购买更昂贵的绿色食品， 那就值得担忧了。
>57 Lighthouses
The first navigational lights in the New World were probably
lanterns hung at harbor entrances. The first lighthouse was put up by
the Massachusetts Bay Colony in 1716 on Little Brewster Island at the
entrance to Boston Harbor. Paid for and maintained by "light dues" levied
on ships, the original beacon was blown up in 1776. By then there were only
a dozen or so true lighthouses in the colonies. Little over a century
later, there were 700 lighthouses.
The first light erected on the West Coast in the 1850's featured the same
basic New England design: a Cape Cod dwelling with the tower rising from
the center or standing close by. In New England and elsewhere, though,
lighthouses reflected a variety of architectural styles. Since most
stations in the Northeast were built on rocky eminences, enormous towers
were not the rule. Some were made of stone and brick, others of wood or
metal. Some stood on pilings or stilts; some were fastened to rock with
iron rods. Farther south, from Maryland through the Florida Keys, the coast
was low and sandy. It was often necessary to build tall towers there -
massive structures like the majestic Cape Hatteras, North Carolina,
lighthouse, which was lit in 1870. At
190 feet, it is the tallest brick lighthouse in the country.
Notwithstanding differences in appearance and construction, most
American lighthouses shared several features: a light, living quarters and
sometimes a bell (or later, a foghorn).They also had something else in
common: a keeper and, usually, the keeper's family. The keeper's
essential task was trimming the lantern wick in order to maintain a
steady, bright flame. The earliest keepers came from every walk of life -
they were seamen, farmers, mechanics, rough mill hands - and appointments
were often handed out by local customs commissioners as political plums.
After the administration of lighthouses was taken over in 1852 by the
United States Lighthouse Board, an agency of the Treasury Department, the
keeper corps gradually became highly professional.
灯塔在新大陆上，最初的航标灯要算那些挂在港湾入口的提灯了吧。 最初的灯塔是
1716 年由马萨诸塞湾殖民地在波士顿港入口一个叫小布罗斯特的岛上建起的。 这最初的灯 塔是通过向船只征收"买光钱"来维持运作的，于 1776
年被炸毁。 那时，在各殖民地，真正 的灯塔仅有十几个。 但过了一个世纪多一点，灯塔就增至七百多个了。 1850 年，在西部
沿海建起的首座灯塔基本上沿袭了新英格兰灯塔的设计方案，即那种中心或周围升起塔楼的 典型的哥德角式房子。
新英格兰与其它一些地方的灯塔在建筑风格上是多样化的。 在东北 部，灯塔大都建在石质的高地上，因此塔身不需要太高。 它们有砖石结构的； 也有木材或
金属结构的，有的灯塔建在支架上，有的则用铁条固定在岩石上。 在更南方的地区，从马
里兰到弗罗里达礁群的海岸地势低平且多为沙质，因此高大的塔身就很必要了。 例如 1870 年在北卡罗来纳的哈特拉角建的宏伟的大灯塔，高达 190
英尺，是全美最高的砖结构灯塔。 虽然美国的灯塔在外观和结构上存在一些差异，但它们确有些共同之处，比如都有灯标、有 住房、有时还有钟(后来改用雾角)。
此外，还有一个相同之处，那就是都有守塔人，通常 是守塔人全家。 守塔人的基本工作就是修剪灯蕊，以便火焰明亮而稳定。 最早的守塔人来
自各种行业：海员、农民、技工和干粗活的。 这个职位通常是作为政治回报由地方海关官 员决定任命。 但在 1852
年后，财政部下属的美国灯塔管理委员会接管了所有灯塔，守塔人 这支队伍也逐渐趋向专业化了。
>58 Animals' Compasses
Researchers have found that migrating animals use a variety of inner
compasses to help them navigate. Some steer by the position of the Sun.
Others navigate by the stars. Some use the Sun as their guide during the
day and then switch to star navigation by night. One study shows that the
homing pigeon uses the Earth's magnetic fields as a guide in finding its
way home and there are indications that various other animals from insects
to mollusks, can also make use of magnetic compasses. It is of course very
useful for a migrating bird to be able to switch to a magnetic compass
when clouds cover the Sun; otherwise it would just have to land and wait
for the Sun to come out again.
Even with the Sun or stars to steer by, the problems of navigation are more
complicated than they might seem at first. For example, a worker honeybee
that has found a rich source of nectar and pollen flies rapidly home to the
hive to report. A naturalist has discovered that the bee scout delivers her
report through a complicated dance in the hive, in which she tells the
other workers not only how far away the food is, but also what direction to
fly in relation to the Sun. But the Sun does not stay in one place all
day. As the workers start out to gather the food, the Sun may already
have changed its position in the sky somewhat. In later trips during the
day, the Sun will seem to move farther and farther toward the west. Yet the
worker bees seem to have no trouble at all in finding the food source.
Their inner clocks tell them just where the Sun will be and they change
their course correspondingly.
动物的罗盘
研究人员已经发现迁徙性动物可以借助各种各样的体内罗盘来校正方向。 有些动物借 助太阳的位置辨别方向，有些则依靠星星。
还有的白天利用太阳，晚上利用星星。 有研究 发现信鸽以地磁场为向导来找到回家的路。 还有迹象表明许许多多其它生物，从昆虫到软
体动物，也能利用这种磁场罗盘。 具有这种磁场罗盘，对候鸟来说当然非常有用，因为如
果乌云遮日，它可以以磁场为向导继续飞行，否则它就只好着陆，等待太阳重新出现。 即 使是借助太阳或星星导航，其中的学问也比它表面看起来的要复杂得多。
例如，一只工蜂 找到了花圃蜜园，急忙飞回蜂房报信。博物学家发现这只蜂探在蜂房里跳了一段极为复杂的
舞，通过这段舞她不但告诉其它工蜂食物有多远，而且报告了以太阳为参照的飞行路线。 但 太阳不会呆在天上不动。
当蜂群出发采食时，太阳可能已经多少改变了它在天空中的位置。 出发得越迟，太阳就越偏西，可这似乎没给寻找食物源的工蜂们带来任何不便。 它们体内
的时钟告诉他们太阳应在的位置，据此它们相应地改变前进的方向。
>59 Muscles and Human
Body It is in the joints of the human body that movements of the bones
take place. The movement itself is caused by the pull of sheets and
cords of very tough tissue called muscle. Muscle tissue has the special
ability to shorten itself so that the bone on which it pulls has to move.
When muscle tissue shortens, it also bunches up. Muscle tissue covers
the body in sheets and bands that lie between the skin and the skeleton.
The bones are the framework of the body, but the muscles fill out the body
shape. Most muscles extend from one bone to another. When the muscle
between the bones shortens, one bone has to move. The point where the
muscle is fastened to the unmoving bone is called the origin of the
muscle, whereas the point where the muscle is not fastened to the bone
that is to be moved is called the insertion. Sometimes the muscle is not
attached directly to the bone but to a tough, nonstretchable cord, or
tendon, that is attached to the bone. Muscles do not push; they can only
pull. To bend the arm at the elbow, the muscle at the front of the upper
arm has to shorten and bunch up. To unbend the arm other muscles in the
back of the arm have to shorten. These two sets of muscles - the front and
the back - are said to act in opposition to each other. When one set is
working, the other set is usually relaxed. But there are times when both of
them work. Sometimes muscles are called upon to do more than simply pull in
one direction. They may have to perform a turning motion. To be able to do
this, the muscle must be attached to the bone at an angle. By pulling, the
muscle can cause the bone to pivot. A few muscles have special functions.
The diaphragm, for example, forces the lungs to take in air. This part of
breathing is not primarily a bone moving operation.
肌肉和人体 骨骼运动发生在人体的关节部位。这种运动是由称为肌肉的片状或条状的 强韧组织拖动而引起的。
肌肉组织有一种特殊的收缩能力，可以带动与之相连的骨骼。 肌 肉在收缩的同时，也会聚成团。 肌肉以条状或片状形式布满全身，存在于皮肤与骨架之间。
骨骼是身体的支架，而肌肉则构成了人的体形。 大多数肌肉接两块骨头，但当肌肉收缩时 只有一块骨头运动。
肌肉与不动骨相连的一端叫肌起端，与动骨相连的一端叫附着端。 有 些肌肉不与骨骼直接相连，而是连着附在骨骼上的不能收缩的带状组织或腱上。 肌肉不能
推动而只能拉动骨骼。 要从肘部弯曲手臂，就要收缩上臂正面的肌肉。 要伸直手臂，背面 的肌肉就得收缩。
这两组肌肉，正面的和背面的，称为相反运动肌肉。 当一组工作时，另 一组就休息。 但有时它们也一起工作。 有时我们要求肌肉不仅仅做简单的单向拖动。
它 们需要转动。 但只有当肌肉与骨骼形成一定角度时，它们才能转动，从而拖动骨骼绕某个 轴旋转。 有几块肌肉的作用较特殊，例如隔膜肌。
它带动肺部吸入空气。 呼吸基本上不 是骨骼运动带动的。
>60 Colds and Age
A critical factor that plays a part in susceptibility to colds is age. A
study done by the University of Michigan School of Public Health revealed
particulars that seem to hold true for the general population. Infants are
the most cold ridden group, averaging more than six colds in their first
years. Boys have more colds than girls up to age three. After the age of
three, girls are more susceptible than boys, and teenage girls average
three colds a year to boys' two. The general incidence of colds continues
to decline into maturity. Elderly people who are in good health have as few
as one or two colds annually. One exception is found among people in
their twenties, especially women, who show a rise in cold infections,
because people in this age group are most likely to have young children.
Adults who delay having children until their thirties and forties
experience the same sudden increase in cold infections. The study also
found that economics plays an important role. As income increases, the
frequency at which colds are reported in the family decreases. Families
with the lowest income suffer about a third more colds than families at the
upper end. Lower income generally forces people to live in more cramped
quarters than those typically occupied by wealthier people, and crowding
increases the opportunities for the cold virus to travel from person to
person. Low income may also adversely influence diet. The degree to
which poor nutrition affects susceptibility to colds is not yet clearly
established, but an inadequate diet is suspected of lowering resistance
generally.
感冒与年龄
年龄是人们是否易患感冒的一个重要因素。 密歇根大学公共卫生学院揭示了一些对人 们普遍适用的细节。
婴儿期是最易感冒的时期，从出生到一周岁平均感冒六次。 在三周岁 前，男孩比女孩感冒次数要多。 但三周岁后，女孩就更易感冒了。 十几岁的女孩年平均感
冒三次，男孩则为两次。 一般说来，随着年龄的增长，感冒的次数也越来越少。 健康的老 年人每年只感冒一至两次或更少。
但在二十至三十岁之间的人尤其是妇女出现了例外。 他 们感冒的次数有所增加，其原因在于人们通常在这一时期带养小孩。 那些晚育至三十几岁
或四十几岁才有孩子的人，在那一时期感冒次数也会突然增加。 研究还发现，经济状况与 感冒息息相关。 随着收入的增加，家庭成员的感冒次数呈下降趋势。
家境贫寒的人感冒次 数要比最富裕的人多三分之一。 低收入者被迫挤住在比富人居所狭小得多的空间里。 拥挤 的状况为感冒病菌的传播提供了条件。
低收入同样不利于合理的饮食结构。 营养不良到底 对患感冒造成多大的影响目前尚不清楚，但不合理的饮食通常降低了人体的抵抗力。
>61 Pottery
Ancient people made clay pottery because they needed it for their
survival. They used the pots they made for cooking, storing food, and
carrying things from place to place. Pottery was so important to early
cultures that scientists now study it to learn more about ancient
civilizations. The more advanced the pottery in terms of decoration,
materials, glazes and manufacture, the more advanced the culture itself.
The artisan who makes pottery in North America today utilizes his
or her skill and imagination to create items that are beautiful
as well as functional, transforming something ordinary into something
special and unique.
The potter uses one of the Earth's most basic materials, clay. Clay
can be found almost anywhere. Good pottery clay must be free from all
small stones and other hard materials that would make the potting
process difficult. Most North American artisan potters now purchase
commercially processed clay, but some find the clay they need right in the
earth close to where they work.
The most important tools potters use are their own hands; however, they
also use wire loop tools, wooden modeling tools, plain wire, and sponges.
Plain wire is used to cut away the finished pot from its base on the
potter's wheel.
After a finished pot is dried of all its moisture in the open air, it is
placed in a kiln and fired. The first firing hardens the pottery, and it is
then ready to be glazed and fired again.
For areas where they do not want any glaze, such as the bottom of the pot,
artisans paint on melted wax that will later burn off in the kiln. They
then pour on the liquid glaze and let it run over the clay surface, making
any kind of decorative pattern that they want.
陶器古代人制作陶器是因为他们的生存需要它。 他们用这些自制的盆盆罐罐来做饭、 装食物、储运东西。
陶器在早期文化中占据了如此重要的地位，以致于科学家们现在通过 研究陶器来获取对古代文明的更多的了解。 因为陶器的装饰、材料、釉彩、制作等工艺越
发达就说明这种文明越发达。 今天，北美的陶艺匠人运用他们的技艺和想象力创造出了既 美观又实用的陶艺制品，把日常用品变为独特的艺术品。
制陶匠人使用大地上最基本的原
材料--粘土。 粘土几乎随处可见，但好的制陶所用的粘土必须不含小沙粒或任何硬物，否 则会给制陶过程带来不便。
现在大多数北美制陶艺人买现成的专用陶土，也有些陶匠乐于 就地取材，在作坊附近自己挖粘土。 制陶器最重要的工具是工匠们自己的双手，但有时他
们也用些别的工具，如绳圈、木模、素线、海绵等。 素线的作用是当一件陶器完成后用它 把陶器从转盘上的基座上切下来。
陶器成形后，首先要在空气中自然风干，再放到窑中焙 烧。 第一遍焙烧使得陶器变得坚硬，下一步就是给它上釉彩，然后再焙烧。 陶器上有些地
方不需上釉彩，像罐子底部，匠人们就在这些部位涂上蜡，一加热就会化掉。 然后匠人们 把釉彩液体浇上陶器表面，绘制他们想要的任何图案。
>62 Mimicry in Plants
Plant adaptations can be remarkably complex. Certain species of orchids,
for instance, imitate female bees, other plants look and smell like dead
animals, and still others have the appearance of stones. These strange
adaptations to life represent just a few of the sophisticated means by
which plants enhan
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