THE KOMANCE OF NATURAL HISTORY. 



habitants : mosses, lichens, and a variety of small 

 herbaceous plants were in the same neighbour- 

 hood ; and, lower down, dwarf-birch, and a species 

 of osier, formed a pretty kind of thicket. The 

 traces of reindeer appeared on the very topmost 

 snow."* 



The very dust of the air is found to be peopled 

 with living plants and animals, and that where 

 we should least have expected to find it so 

 stocked; nay, where we should scarcely have 

 looked for clouds of dust at all,— far out on the 

 lone ocean, hundreds of miles from land. In Mr. 

 Darwin's voyage, he noticed, as he approached the 

 Cape Verd Islands, this curious phenomenon:— 

 "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 infusorial 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 ! The infusoria, with the exception 

 of two marine species, are all inhabitants of fresh 

 water. I have found no less than fifteen different 

 accounts of dust having fallen on vessels when far 

 out in the Atlantic. From the direction of the 



* MS. letter, quoted in Barrow's "Excursions in the North of 

 Europe," p. 359. 

 + Constituting the Diatomaccw of modern science. 

 74 



