Phytoliths: The Storytelling Stones Inside Plants

摘要

Charles Darwin's voyage aboard the Beagle is legendary in the history of science, and yet one of his notable observations is barely known. Before he glimpsed some of the finches that would bear his name and provide the inspiration for the theory of natural selection, he was one of the first scientists to remark on the uniqueness of microscopic silica bodies called phytoliths. On January 16, 1832, the Beagle stopped at its first port of call, Porto Praya in the Cape Verde islands off the northwest coast of Africa. Darwin, the ever-studious naturalist, noted with a sense of wonder the following in his journal, later published in The Voyage of the Beagle: Generally the atmosphere is hazy; and this is caused by the falling of impalpably fine dust, which was found to have slightly injured the astronomical instruments. The morning before we anchored at Porto Praya, I collected a little packet of this brown-coloured fine dust, which appeared to have been filtered from the wind by the gauze of the vane at the masthead. Mr. Lyell has also given me four packets of dust which fell, on a vessel a few hundred miles northward of these islands. Professor Ehrenberg finds that this dust consists in great part of infusoria with siliceous shields, and of the siliceous tissue of plants. In five little packets which I sent him, he has ascertained no less than sixty-seven different organic forms!