In colonies (群体) that range in size from a few hundred to tens of millions, they organize their lives with a clear division of labor. Even more amazing is how they achievethis level of organization. Where we use sound and sight to communicate, ants dependprimarily on pheromone (外激素), chemicals sent out by individuals and smelled or tastedby fellow members of their colony. When an ant finds food, it produces a pheromone that will lead others straight to where the food is. When an individual ant comes under attack or is dying, it sends out an alarm pheromone to warn the colony to prepare for a conflict as a defense unit.

         In fact, when it comes to the art of war, ants have no equal. They are completely fearless and will readily take on a creature much larger than themselves, attacking in large groups and overcoming their target. Such is their devotion to the common good of the colony that not only soldier ants but also worker ants will sacrifice their lives to help defeat an enemy.

         Behaving in this selfless and devoted manner, these little creatures have survived on Earth, for more than 140 million years, far longer than dinosaurs. Because they think as one, they have a collective (集体的) intelligence greater than you would expect from itsindividual parts.

    For the Travel section, writers and editors selected special items to profile from a dozen cities.

Brussels:Chocolate

    Nearly half the chocolate consumed in the world is eaten in Europe, and Belgium—with average consumption of 14.99 pounds per person a year—certainly covers its fair share. While Brussels, the country's capital, is home to hundreds of chocolate makers, what makes a visit necessary is the rich heritage of traditional chocolate makers.

Budapest: Paprika (红辣椒)

    The job of preparing Hungarian paprika was once considered too dangerous for mothers to do. A woman who touched her children upon returning from work risked burning them, so only the elderly and unmarried were allowed the delicate task of separating the skin from the flesh. But by the early 20^th century, sweeter varieties and a machine turned paprika into a common feature of all Hungarian cuisine.

Lisbon: Tiles (瓷砖)

    Is there a bluer Country than Portugal? The blue sky and Atlantic Ocean embrace the land. The blue moods of Fado, the dark folk music, form the national soundtrack. And all across Portugal, the typically blue designs of azulejos—ceramic tiles—are spread across churches, castles, palaces, university halls, parks... The result is a beautiful land of Christian saints, Portuguese kings, historical glories, aristocrats at leisure, seascapes and so on.

Madrid: Guitars

    Walking into one of Madrid's storied guitar makers' workshops can feel like stepping into the past. Curly wood shavings, from the palest pine to ebony, fall onto the floor as artisans turn some humble wood into works of art. It's painstaking work—all done by hand—with classical guitar models and the methods of making them changing little over the last century.

    A complaint was received by the president of a major car company:“This is the fourth time I have written to you , and I don't blame you for not answering me because must sound crazy, but it is a fact that we have a tradition in our family of having ice-cream for dessert after dinner each night. Every night after we've eaten, the family votes on which flavor(味道)of ice-cream we should have and I drive down to the store to get it. I recently purchased a new Pantsmobile from your company and since then my trips to the store have created a problem. You see, every time I buy vanilla(香草)ice-cream my car won't start. If I get any other kind of ice-cream, the car starts just fine. I want you to t now I'm serious about this question , no matter how silly it sounds: What is there about a Pantsmobile that makes it not start when I get vanilla ice-cream, and easy to start whenever I get any other kind?'

    The Pantsmobile company president understandably doubted about the letter, but he sent an engineer there anyway. The engineer had arranged to meet the man just after dinner time, so the two got into the car and drove to the grocery store. The man bought vanilla ice-cream that night and sure enough, after they came back to the car it wouldn't start for several minutes. The engineer returned for three more nights. The first night, the man got chocolate. The car started right away. The second night, he got strawberry and again the car started right up. The third night he bought vanilla and the car failed to start.

    There must be a reason why the man's car wouldn't start when he bought vanilla ice-cream. What was it? After doing more research into the case, the engineer eventually found out. The cause. Vanilla ice-cream was the most popular flavor and was on display in a little case near the express check out, while the other flavors were in the back of the store and took more time to choose and check out. This mattered because the man's car was experiencing vapor(蒸汽) lock, which is excess(过度的)heat boiling the fuel in the fuel line and the resulting air bubbles (气泡) blocking the flow of fuel until the car has enough time to cool. When the car was running, there was enough pressure to move the bubbles along, but not when the car was trying to start.

    Looking out the window of his truck, Bob Fitzgerald sees large, undesirable plants growing in the fields. Visitors to his neighborhood around the Chesapeake Bay mainly see dying forests and empty farmland. Fitzgerald says the land has been in his family since the 17th century, and it has been sinking for hundreds of years. As sea levels rise salt water is entering rivers and other waterways. As a result, the ground is becoming too salty for crops to grow.

    Around the world, scientists warn that coastal (沿海 ) farms are under threat from rising seas and salt water. A World Bank report predicts that rice production in coastal areas may fall by 15 percent by the year 2050. Another study found that hundreds of millions of people will be forced to move inland because of rising waters.

    Kate Tully, an agroecologist(农业生态学家) wants to keep coastal farmers in business as the seas rise. The United States Department of Agriculture gave Tully and other researchers $ 1.1 million to study the problem. She and her team hope to give farmers ways to stay on their land. She told media that they are testing different crops on pieces of land around the coastal areas.

    "Sorghum is my new favorite crop because it can grow without rain and it can grow with lots of rain. So this is actually a pretty good option." The grain crop may be a good choice to feed the nearly 600 million chickens raised in the area each year. As farmers know, chickens can deal with salt, dry weather conditions and heavy rains. Tally's group is also testing other kinds of grain and a few crops that they believe can grow in the salt.

    Yet just being able to grow a crop is not enough. The crop has to be profitable. So an economist on the team will be looking at the numbers. But continuing to farm the land may not be the best plan of action. Some people believe the land should he given back to nature. They say the fields should be turned into wetlands, which are popular with duck hunters. "There's money in duck hunting," fully said. Hunting organizations will pay farmers for a permit to hunt on their land. Farmers could earn a lot of money from duck hunters, she said.

    Tully and her team are just getting started. It will be a few years before they really understand how to save the farms.

    Over the past century, an alarming number of animals have become endangered or even extinct. Below are some animals whose numbers have been rapidly dropping in recent years.

    Panda Bear

    One of the biggest reasons contributing to the decline in the panda species is the destruction of its natural habitat. Farmers in China have gradually been claiming more and more of the land. As a result, pandas are forced to move away to places where it is hard to find bamboo for food.

    Green Turtle

    The green sea turtle species has survived for several millions of years, so you might wonder why it's only becoming endangered now. A major cause is the change in climate and temperature, which both affect the hatching rates of turtle eggs. Climate changes also cause violent weather and rising water levels to flood areas where turtles usually go to lay their eggs. Apart from this, oil spills and other poisonous pollution, as well as increased fishing activities can cause sickness, or even death to the green turtles.

    Cheetah

    Cheetahs are famous for being the fastest animal on land but even they can't run from some of the larger threats that have harmed them. Like the panda bears, cheetahs have gradually been losing their natural homes due to humans claiming land and developing in those areas. To make matters even worse, smaller animals move away when these areas are occupied, which means that the cheetah has less food! Don't forget that other large animals, such as lions, are also fighting for any food that they can find, so occasionally young cheetahs end up as prey too.

    Indian Elephant

    Elephants are extremely intelligent animals and also the largest mammals that live on land. Sadly, in Asia many elephants were killed so that people could remove their tusks to use as decorative objects. While this practice has been banned now, some people still illegally continue. Forests in India have also been steadily destroyed and elephants are sometimes killed when they end up on human territory.

    It has been described as art by some people, but to others it's an ugly part of modern life. What is it? Graffiti (涂鸦), of course. Look around cities in the UK today and you can see graffiti on buildings, walls, doors and even on buses or trains that have stayed in one place for too long. But where modern technology creates a problem, it also finds a way to deal with it. Last week, The Weekend West was shown around the factory of a small but successful company, Hubdean.

    Hubdean's achievement is a series of special paints which are graffiti-resistant. How do they work? It couldn't be simpler. Take any graffiti-covered surface. First, a treatment called Agproclear is used. Then, using a very hot pressure jet (压力喷嘴), this treatment is taken away and the graffiti disappears at the same time. Now you have a clean wall. But before this clean wall can be painted on by graffiti lovers, a new product, Agproshield, is used. This paint has a special surface which gives it two important advantages. Firstly, spray paint (喷雾颜料) won't stick to the surface very well, and secondly, the whole surface can be cleaned very easily, just using water. Once the surface is painted, no specialist equipment is needed to keep the area clean and graffiti-free.

    Not surprisingly, Hubdean's products are used by both local governments and private companies all over the UK, and now orders are being received from around the world. This brings the company a problem, however. Can they increase production to satisfy the needs? Of course, they can build a second factory or work with a large international company to make their products. The future is looking good for Hubdean!