在转板藻属(Mougeotia)绿藻的每个细胞里,都有一个大的、板状的叶绿体。叶绿体通过自身的微妙的倾斜,对射入光线发生反应。在暗淡的或中等强度光照下,叶绿体以其宽阔的表面迎着光线;而在强光照射时,它却转而以其边缘对着光线,以避免在强光下面有害的过度暴露。是什么东西驱使藻类叶绿体做这种对光线强弱适应的运动的呢?最近,西德科学家发现,一些明显的、象肌肉样的纤维连接在藻类的叶绿体上, In every cell of the genus Mougeotia, there is a large, plate-shaped chloroplast. The chloroplast reacts to the incoming light through its own subtle tilt. In darkened or moderately intense light, the chloroplasts greet their broad surfaces with light; in bright light, however, they switch to light with their edges to avoid detrimental overexposure under bright light. What drives the algal chloroplasts to do this exercise that is adapted to light intensity? Recently, scientists in West Germany found that some obvious, muscle-like fibers are attached to the algal chloroplasts,