「音频+中英文稿」Why is（cotton in everything）

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Centuries ago, the Inca developed ingenuous suits of armor

几个世纪前， 印加人发明了一种独特的盔甲，

that could flex with the blows of sharp spears and maces,

这种盔甲能够随着锋利长矛 和狼牙棒的打击而弯曲，

protecting warriors from even the fiercest physical attacks.

从而保护士兵免受于 哪怕是最猛烈的物理攻击。

These hardy structures were made not from iron or steel,

这些坚固的结构 并不是由铁或钢制成的，

but rather something unexpectedly soft: cotton.

而是由一个极其柔软的材料制成：棉花。

These thickly woven, layered quilts of cotton

这些厚厚编织、层层堆叠的棉花

could distribute the energy from a blow across a large surface area,

能够将击打的力量 分散在一块较大的表面积，

shielding warriors without restricting their mobility.

因此在保护士兵的同时， 也不会局限他们的活动能力。

These seemingly contradictory features—

这些看似相互矛盾的特性——

strength and flexibility, softness and durability—

强硬度和灵活性、 柔软度和耐用性，

have their roots in the intricate biology of the nearly invisible cotton fiber.

来源于复杂生物学中 肉眼几乎无法看见的棉纤维。

These fibers begin life deep within a cotton flower,

这些纤维的生命始于

on the surface of a seed.

棉花花朵表面的种籽。

As many as 16,000 fibers will festoon a single seed,

一个种子中能被 多达 16,000 根的纤维充斥，

bulging from the seed’s surface like miniature water balloons.

宛如迷你水气球， 从种子表面向外膨胀。

Each cotton fiber, no matter how large it grows,

不论长成多大个， 每根棉纤维

is made of just one cell.

都仅由单个细胞构成。

That cell has multiple layers of cell wall.

这种细胞有好几层细胞壁。

After a few days, the sides of the first layer,

几天后，第一层细胞壁，

called the primary cell wall,

亦称为初生细胞壁，

stiffen, pushing cell growth in one direction

变硬，向一个方向推动细胞生长，

and causing the fiber to elongate.

从而使纤维被拉长。

The fiber elongates quickly for about 16 days.

在 16 天左右的时间， 纤维被快速拉长。

Then it begins the next stage: strengthening the cell wall.

其后，它便进入下一个生长阶段：强化细胞壁。

It does this by making more of the carbohydrate cellulose.

这是通过产生更多的 碳水化合物纤维素来完成的。

Cellulose will make up 34% of the cell wall at this stage

在这一阶段，该纤维素 占细胞壁构成成分的 34%，

and swiftly increases.

且占比仍旧快速上升。

This new growth also reinforces the cell wall

这一生长促使 对现有细胞壁纹理的抵触，

by going against the grain of the existing wall.

因此也强化了细胞壁。

The strengthened wall is more rigid, restricting further growth.

被强化的细胞壁变得更加坚硬， 会限制其进一步生长。

That means if the fiber remodels its walls too early,

这意味着如果纤维素过早 改变细胞壁结构，

it will be short,

棉花纤维就会很短，

and ultimately make rough, weak fabrics.

最终只能产出粗糙且易破的布料。

But if cell wall strengthening begins too late,

但如果细胞壁强化阶段开始得过晚，

the wall won’t be sturdy enough—

那层细胞壁就会不够坚固，

producing fibers that are too weak to hold fabrics together well.

生成的纤维会过为柔弱， 难以很好地将布料合成。

In ideal growing conditions—

理想的生长条件是：

with the right temperature, water, fertilizer, pest control, and light—

适宜的温度、水、肥料、 害虫防治，还有光线。

a cotton fiber can grow up to 3.6 centimeters long

这样，一根棉纤维 可以生长至长 3.6 厘米，

with only a 25 micrometer width.

宽仅为 25 微米。

Long, fine fibers can wrap around one another

细长且高品质的纤维 相较于短且质量较次的纤维，

better than shorter, less fine fibers,

能更好地缠绕彼此。

which means those long, fine fibers make stronger threads

这表示那些细长且高品质的 纤维能够制造出更坚韧的棉线，

that hang together better as fabric.

编织成更好的面料。

Cotton with these qualities has diverse uses—

因为棉花的特性， 它们被广泛使用，

from soft textiles to the U.S. dollar bill,

从柔软的纺织品到美元纸钞——

which is 75% cotton.

内含 75% 的棉成分。

The next crucial stage of the cotton fiber’s growth

在下一个棉花纤维 成长的关键阶段，

begins as it thickens its secondary cell wall

大量纤维素在次生细胞壁内

by depositing large quantities of cellulose into the secondary layer.

堆积并从而强化细胞壁。

Cellulose goes on to make up over 90% of the fiber’s weight.

纤维素的重量占比上升， 超过纤维净重的 90% 。

The more cellulose that gets deposited,

越多纤维素堆积，

the denser that secondary layer becomes—

次生细胞壁 就变得更紧实——

and this determines the strength of the final fiber.

这决定了最终棉花纤维的强度。

This stage is essential for developing long-lasting material

对于后阶段是否能产出 经久耐用的材料，比如 T 恤，

for the likes of, say, a t-shirt.

这一生长阶段至关重要。

The garment’s capacity to withstand years of washing and wear

一件成衣经受多年穿洗的能力

is largely determined by the density of that secondary cell wall.

很大程度上 取决于次生细胞壁的密度。

On the other hand,

从另一方面来说，

its softness is strongly influenced by the length of the fiber,

成衣的柔软性 主要受到棉纤维长度的影响，

established with the remodeling of the primary wall layer.

而纤维长度是由 初生细胞壁重塑的。

Finally, after about 50 days, the fiber is fully grown.

终于，在大约 50 天后， 纤维生长完毕。

The living matter within the cell dies off,

细胞死亡，

leaving behind only the cellulose.

只留下纤维素。

The dried cotton seed pod, or boll, that surrounds the fibers cracks open,

包裹纤维的干燥的 棉籽荚，也叫棉铃裂开了，

unveiling a burst of several thousand fiber cells in a fluffy mass.

露出一簇簇柔软蓬松的纤维细胞。

The thread-like fibers we see— thinner than a human hair—

我们看到的丝状纤维—— 比人类毛发还要细——

are the remains of those dense, dried out walls of cellulose.

是那些紧实干燥的 纤维素壁（原细胞壁）的残留物。

Tens of thousands of these fibers spun into yarn

数以万计的这些纤维被纺织成纱线，

will go on to make everything from fabric, to coffee filters, diapers,

随后继续加工生产为各种东西， 从面料织物，到咖啡过滤器、尿布，

and fishing nets.

还有渔网。

And with the help of modern science,

利用现代科学的帮助，

cotton might soon be softer, stronger, and more resilient than ever

调整营养、气候和基因等学科因素，

as researchers investigate how to optimize its growth

科研人员正在研究如何优化棉花生长。

based on nutrients, weather conditions, and genetics.

棉花可能在不久将来 变得更柔软、更坚硬，以及更有韧性。

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