Bioluminescence, unlike other sources of light（the sun, fire, light bulbs）, which produce energy from heat, is defined as “the emission of light from living organisms（such as fireflies and bacteria）as the result of internal chemical reactions”. It is one of the wonders of nature that just about any of us can witness.

While a few organisms can produce bioluminescent light outside of the oceans（think fireflies）, most of the bioluminescence going on is in salt water. In fact, the vast majority of bioluminescent organisms evolved in order to provide light in deep sea marine ecosystems—either to light up prey or as a warning against predators（捕食者）—far below sunlight's reach into the water column.

Humans have been putting natural bioluminescence to work for a while—19th century coal miners would trap fireflies（instead of open-flame candles or lanterns that could cause explosion）in jars to light their way. But nowadays researchers are hard at work synthesizing（合成）the chemical reactions behind bioluminescence for a range of modern-day applications.

Using bioluminescence to help cure disease is a big focus of some biomedical research companies, given the promise of using heat-free organic light to detect metastasizing（转移的） cancer cells, stem cells, viruses or bacteria within living tissue. The military also has big hopes for applying the chemical reactions of bioluminescence to create light that won't cause the heat-seeking sensory equipment of the enemy whether on land，at sea or in the sky. Some other practical applications of bioluminescence include an effort to connect genes from bioluminescent organisms into trees that would light up when the sun sets.

While none of these “technologies” is yet ready to become mainstream, it's good to know that the future looks bright.

【小题1】What exactly causes biolunninescence?

A．Heat energy.

B．Chemical reaction.

C．Salt water.

D．Living organism.

【小题2】Why did miners use fireflies instead of lanterns in the 19th century to light up?

A．To ensure safety.	B．To seek comfort.
C．To provide convenience	D．To save money

【小题3】What may bioluminescence help to be used as?

A．The heat-seeking sensory equipment	B．A simple cure for all kinds of diseases.
C．An all-natural alternative to street lights.	D．An effective virus-killer within living tissues.

【小题4】What is implied in the last paragraph?

A．The good and bright future should be ours.

B．Bioluminescence is widely used in our life.

C．The technologies are good enough to apply.

D．The search is on for the use of organic light sources.