l80 ROMANCE OF LOW LIFE AMONGST PLANTS. 



formed of felspathic silt, no doubt the product of 

 glacial streams and siliceous cells of Diatomaceaj. 

 It much resembled, he says, " the fossil or meteoric 

 paper of Germany, which is also formed of the lowest 

 tribes of fresh- water plants." ^ 



Dust Showers. 



Many accounts have appeared, from time to time, 

 of dust showers, which puzzled the curious for many 

 years, until the discovery was made by Ehrenberg 

 that they were composed for the most part of micros- 

 copic organisms, of which the greater proportion were 

 minute diatoms. The number of showers which 

 Ehrenberg records is 340, of which 81 dated before 

 the Christian era, and 249 since. Details of some 

 of the more recent are given ; for instance, in the 

 Atlantic, about five hundred miles from the coast 

 of Africa, " the dust was collected by Mr. Darwin 

 from the ship in which he was at the time. The 

 direction of the wind was from the African coast. 

 The dust resembled volcano ashes, although evidently 

 not of this origin, and about a sixth part of it was 

 siliceous shells of fresh-water and land Infusoria 

 (diatoms), and siliceous phytolites — eighteen species 

 of the former, and as many of the latter. Most of 

 the forms are European, and none exclusively African. 

 Among them was the South American species, Hi- 

 inantidiiim pnpillo, which occurs in Cayenne, and also 

 a Snrirella, probably from the same continent." The 

 conclusion follows, as Ehrenberg observes, that either 

 the dust came in part from South America in the 

 ' Himalayan Journal, vol. ii, p. 132. 



