【正文】 This fivesecond film appears to show movement, with small white objects crossing the camera39。s field of vision.ESA39。s scientists were quick to point out that any movement seen was likely to be an artefact that owed its existence to nothing more than the fact that the images had not been put together correctly. Whether that interpretation is correct should be clear when ESA39。s own “official” movie is released, which had not happened as The Economist went to press.Nevertheless there is, privately, a debate among planetary scientists as to whether the white blobs are an artefact, or pieces of ice being carried past the lander on a thin stream of liquid hydrocarbon a few centimetres deep.That would be exciting. A stream is a stream, whether it is made of water or hydrocarbon. At the moment, Earth is the only body known to have them. But, as Ralph Lorenz, a planetary scientist at the University of Arizona, points out, the lesson from places such as Mars—and indeed Arizona—is that features created by liquids may exist, but the processes that carved them may be transitory or long gone. It is possible that rare but violent events, rather than continuous erosion, are responsible for shaping Titan39。s landscape. Whether Huygens has collected enough data to tell the difference remains to be seen.Passage 5Greener than you thoughtGenetically modified sugar beet is good for the environmentThough often conflated in the public mind, arguments against the planting of genetically modified (GM) crops fall into two distinct groups. One, which applies only to food crops, is that they might, for some as yet undemonstrated reason, be harmful to those who eat them. The other, which applies to them all, is that they might be bad for the environment.Proponents of the technology counter that in at least some cases GM crops should actually be good for the environment. Crops that are modified to produce their own insecticides should require smaller applications of synthetic pesticides of the sort that Greens generally object to. But in the case of those modified to resist herbicides the argument is less clearcut. If farmers do not have to worry about poisoning their own crops, environmentalists fear, they will be more gungho about killing the wild plants that sit at the bottom of the food chain and keep rural ecosystems going—orweeds, as they are more monly known.Research just published in the Proceedings of the Royal Society suggests, however, that it may be possible for all to have prizes. Get the dose and timing right and you can have a higher crop yield and a higher weed yield at the same time—and also use less herbicide.The research was done at Broom39。s Barn Research Station in Suffolk, by a team led by Mike May, the head of the station39。s weeds group. The team was studying GM sugar beet. This was one of the species examined in the British government39。s FarmScale Evaluations (FSEs) project, a huge, threeyearlong research programme designed to assess the effects (including the environmental effects) of herbicide use on GM crops.The results for sugar beet, which petes badly with mon weed species and thus relies heavily on the application of herbicides for its success, came in for particular criticism from environmentalists when the trials concluded in 2003. They indicated that fields planted with GM beet and treated with glyphosate, the herbicide against which the modification in question protects, had fewer weeds later in the season. These produced fewer seeds and thus led to reduced food supplies for birds. Some invertebrates, particularly insects, were also adversely affected.The Broom39。s Barn researchers, however, felt that this problem might be overe by changing the way the glyphosate was applied. They tried four different treatment “regimes”, which varied the timing and method of herbicide spraying, and pared them with conventional crop management regimes such as those used in the FSEs.The best results came from a single earlyseason application of glyphosate. This increased crop yields by 9% while enhancing weedseed production up to sixteenfold. And, as a bonus, it required 43% less herbicide than normal. Genetic modification, it seems, can be good for the environment, as well as for farmers39。 pockets.Passage 6Corpus colossalHow well does the world wide web represent human language?LINGUISTS must often correct lay people39。s misunderstandings of what they do. Their job is not to be experts in “correct” grammar, ready at any moment to smack your wrist for a split infinitive. What they seek are the underlying rules of how language works in the minds and mouths of its users. In the mon shorthand, linguistics is descriptive, not prescriptive. What actually