提 要

有時，眼見不能為憑，以著名的「艾賓豪斯錯覺」（Ebbinghaus illusion）為例：許多人會覺得右邊的橘球比左邊的大，其實上兩個一般大。

通常以鄰近物體估算目標物大小的大腦，易受周遭環境誤導。

至於在寒風中發抖的猴子，則被自己誤導：一心想找火取暖，所以忽略了其他可行的辦法。

It was a silent night, the weather was freezing cold. A group of monkeys was shivering on a tree. They were clinging to its branches. One of the monkeys said, "I wish we could find some fire. It will help us to keep warm."

Suddenly they noticed a flock of fireflies. One of the young monkeys thought it was fire. He caught a firefly, and put it under a dry leaf and started blowing at it. Some other monkeys also joined in his efforts.

In the meanwhile, a sparrow came flying to its nest which was on the same tree the monkeys were sitting on. She noticed what they were doing. The sparrow laughed. She said, "Hey silly monkeys, that is a firefly, not real fire. I think all of you should take shelter in a cave."

The monkeys did not listen to the sparrow. They continued to blow at the poor firefly.

After quite a long time, the monkeys became very tired. Now they realized that what the sparrow had said was correct. They set free the firefly and moved to a nearby cave.

The secret of the fireflies

Scientists have long known what causes the yellow, orange or sometimes even blue flickers of light that fly around our back yard on summer evenings. They are the fireflies, also known as lightning bugs, and they have fascinated scientists and laypeople alike for ages. About 2000 species of fireflies exist today, and they mostly live in warm environments. These insects are actually beetles and belong to the family Lampyridae.

What causes those flickers? Scientists have known the basics all along – oxygen, magnesium, calcium, and luciferin, a chemical that is naturally occurring –that causes the bioluminescence from the firefly’s abdomen.

However, the actual chemical reactions that cause the firefly’s light have been a mystery. Bruce Branchini at Connecticut College, and his colleagues seem to have solved the mystery. The findings of their study were recently published in the Journal of the American Chemical Society, and it sheds light on the chemistry that lies behind the bioluminescence.

Branchini’s studies showed that the oxygen responsible for the firefly’s glow is in a special form: a superoxide anion. It is a form of molecular oxygen-containing an extra electron. This enables the oxygen to react with luciferin, to produce the glow.

The study group of chemical biologist Stephen Miller, at the University of Massachusetts Medical School, said that this phenomenon is important as an area of research because luciferin has potential uses in the medical field. For example, a team of scientists including Miller used luciferin to detect specific enzymes in the brains of living rats, which could lead to identifying a method of looking at the hidden mysteries of the human brain.

Who knew that the humble firefly had so much chemistry in it! And so much promise for science.

解 說

在一個寂靜的夜晚，天氣冷得幾乎要結冰。一群顫抖著的猴子待在樹上、緊緊地抓住樹枝。其中一隻猴子說：「希望我們能找到一些火，它能幫助我們保暖。」

突然間，猴子們發現了一群螢火蟲，其中一隻幼猴認為那是火，牠逮到一隻螢火蟲，把蟲放在一片乾燥的樹葉下面，開始對著牠吹氣，其他的猴子也加入了牠的「生火」行列，一起努力吹氣。

就在這個時候，一隻回巢的麻雀飛到這群猴子的同一棵樹上。牠看見這些傢伙正在做的事……麻雀笑了。牠說：「嘿，傻猴子，那是一隻螢火蟲，不是真的火。我想，你們所有人都應該到洞裡避寒。」

猴子沒聽麻雀的勸。牠們繼續向那隻可憐的螢火蟲吹氣。

經過相當長的一段時間之後，猴子們變得非常疲憊。現在牠們發覺麻雀剛才所說的是對的。牠們放走了螢火蟲，找到最近的一個洞穴，擠到面抱著取暖裡。

螢火蟲的祕密

科學家很早前就知道，夏天晚上在後院飛來飛去的黃色，橙色或有時甚至是藍色的閃爍光點是什麼，牠們是螢火蟲，也被稱為閃光蟲。牠們讓多科學家與民眾著迷。目前約有二千種螢火蟲，大多生活在溫暖的環境中。這些昆蟲是屬於螢科的甲蟲。

是什麼導致螢火蟲閃爍？科學家們掌握基本原理：氧氣、鎂、鈣和螢光素，一種天然的化學物質，會引起螢火蟲腹部的生物發光。

然而，實際引起螢火蟲發光的化學反應一直是個謎。康乃狄克學院的科學家布蘭契尼與他的同事，似乎已經解開了這謎團。他們的研究結果最近發表在《美國化學學會》雜誌上，它揭示了生物發光背後的化學反應。

布蘭契尼的研究顯示，負責螢火蟲發光的氧氣是一種特殊的形式：超氧陰離子。它是一種含有分子氧的額外電子。這使氧氣能夠與螢光素反應，產生光亮。

馬薩諸塞大學醫學院的化學生物學家斯蒂芬米勒研究團隊表示，這種現象在研究領域很重要，因為螢光素在醫學領域有潛在用途。例如科學家使用螢光素檢測活鼠大腦中的特定酶，可能找到觀察人類大腦隱藏奧祕的方法。

誰會想到，小小的螢火蟲有如此多的化學成分，又讓科學有如此多可期待的前景。