275 
which is white and frothy in appearance, and of a sweet 
taste. ‘To explain, satisfactorily, all of these phenomena I 
shall begin with the first—the yellow rain or showers of 
sulphur. When engaged at Dartmouth College during the 
last summer, one of my students, Mr. G. F. Stackpole, 
brought me a quantity of a yellowish powder which he 
assured me had fallen in great quantity during a heavy 
shower of rain near Lebanon, N. H., and there covered, not 
only the corn-fields, but the water of Shaker Pond, a respect- 
ably sized sheet of water. On the leeward side of the pond 
this powder had collected in considerable amount, and from 
thence that he brought me had been procured. Such 
showers were not very uncommon in that region, and were 
usually supposed to be, and were called “sulphur.” I 
assured him it was not sulphur, and showed him under the 
microscope what it was. Thereafter, on careful inquiry I 
found, as I had suspected, that the quantity fallen, (for it did 
descend from the air) was by no means as great as he and 
his informants had supposed, and was to be found only on 
one corn field, and on the surface of the water at the side of 
the pond where he had gathered it. Now what was this 
substance. Simply the pollen of the Pine tree, which it shed 
at this season (June—July) in considerable quantity, and I 
found that on the opposite side of the pond to that where the 
gathering had been made was a large grove of such trees in 
blossom. Now I strongly suspect, though, of course I can 
not speak positively without examining specimens, that the 
‘‘vellow clayish substance” mentioned by Mr. Ernst was 
some such pollen, and that his “ 7riceratium” and “ Cosma- 
arvuum” are neither Diatoms nor Desmids, but simply pollen 
granules, which resemble those organisms very. closely in 
outline and sculpture. Ido not see how any force of wind 
could carry up either Diatoms or Desmids, and certainly, as 
far as my experience or that of other observers as yet 
published goes the marine genus Zriceratiwm has never been 
found associated with the fresh water Cosmarium. The 
‘““ Red Snow ” has been, and is still very commonly supposed 
to be a perfect plant, and has been called Hematococcus 
