In nature, nitric oxide is a formidable toxin and a common component of air pollution. 在大自然中，一氧化二氮是一种极为可怕的有毒气体，它是造成空气污染的罪魁之一。

So scientists were naturally a little surprised when, in the mid-1980s, they found it being produced in a curiously devoted manner in human cells. 20世纪80年代中，科学家们发现人类细胞中不断产生这种气体的时候，自然感到有点儿吃惊。

Its purpose was at first a mystery, 一开始，科学家对它的作用感到很困惑，

but then scientists began to find it all over the place—controlling the flow of blood and the energy levels of cells, 但接着就发现它无处不在——控制血液的流量和细胞的能量水平呀，

attacking cancers and other pathogens, regulating the sense of smell, even assisting in penile erections. 进攻癌症及其他病原体呀，调节嗅觉呀，甚至帮助阴茎勃起。

It also explained why nitroglycerine, the well-known explosive, soothes the heart pain known as angina. 这也解释了为什么硝酸甘油，即人们所熟知的炸药，能够缓解心绞痛。

(It is converted into nitric oxide in the bloodstream, relaxing the muscle linings of vessels, allowing blood to flow more freely.) （它在血液中转换为一氧化二氮，使得血管内壁的肌肉放松，血液就可更顺畅地通过了）。

In barely the space of a decade this one gassy substance went from extraneous toxin to ubiquitous elixir. 在不到10年的时间里，这种气体从大自然中的一种外在毒素成了人体内无处不在的灵丹妙药。

You possess "some few hundred" different types of cell, according to the Belgian biochemist Christian de Duve, 根据比利时生物化学家克里斯蒂安·德迪夫的统计，你拥有“约几百种”不同的细胞，

and they vary enormously in size and shape, from nerve cells whose filaments can stretch to several feet 它们的大小和形状有显著的不同：神经细胞呈线状，可以伸展到l米长；

to tiny, disc-shaped red blood cells to the rodshaped photocells that help to give us vision. 红细胞呈盘状；而帮助给我们视觉的光电细胞呈杆状。

They also come in a sumptuously wide range of sizes—nowhere more strikingly than at the moment of conception, 细胞的大小也差别很大——给人印象最深刻的莫过于怀孕的那一刻，

when a single beating sperm confronts an egg eighty-five thousand times bigger than it 一个不甘示弱的精子竟然迎向比它大85000倍的卵子

(which rather puts the notion of male conquest into perspective). （这是男人征服欲的形象化表现）。