1885.1 NEW-YORK MICROSCOPICAL SOCIETY. 177 



rust ; though it is difficult to believe that at any historical time 

 the process of oxidation was not well known even to the most 

 unlearned. Still, we can imagine circumstances under which 

 so simple and ordinary an occurrence might have been magnified 

 into a sanguinary portent. The more reasonable explanation in 

 most instances, however, would be the growth upon the object 

 of a red lichen or alga, as, for example, Hcematococcus sanguineus, 

 or Palmella cruenta. The latter is known also, in popular lan- 

 guage, as Gory Dew, which, as Dr. Carpenter says (" The 

 Microscope and its Revelations," Sixth Edition, p. 292), "is 

 common on damp walls and in shady places, sometimes extend- 

 ing itself over a considerable area as a tough gelatinous mass, 

 of the color and general appearance of coagulated blood." 



3. Showers of Earth, Chalk, Ashes, etc., need no accounting 

 for, in most cases, except upon the theory that, when not simply 

 fictitious, they were probably what they were called ; for the 

 drifting of sands from distant deserts or plains and the wafting 

 of ashes from far-off volcanoes have always been common and 

 well-understood occurrences. So-called rains of brimstone, 

 however, may have been composed of pollen-grains or spores, 

 or other vegetable products, resembling sulphur in coior. Such 

 a fall of pine pollen, which happened in Yokohama, Japan, in 

 April, 1871, is described in "Science Gossip" for 1871, page 

 189. 



4. Showers of Oil were probably never showers at all. The 

 reports concerning them may have been occasioned by the dis- 

 covery upon the earth or upon stones or plants, of greasy 

 spots such as are produced by certain insects and some worms, 

 or they may have arisen from the appearance upon pools of 

 water left by rain of those iridescent films which, we now know, 

 are caused by a variety of substances, including diatoms, iron- 

 bearing earths, and, of course, fat or oil itself. Another cause 

 of this appearance might be one of the gelatinous protophytes, — 

 a Nostoc, for example, or a member of the order Palmellaceae. 

 Describing the beaded filaments of which the Nostochacese con- 

 sist. Dr. Carpenter says (p. 297): "The masses of jelly in 

 which they are imbedded are sometimes globular or nearly so, 

 and sometimes extend in more or less regular branches; they fre- 

 quently attain a very considerable size; and as they occasionally 

 present themselves quite suddenly (especially in the latter part 



