42 POLLEN OF CONIFERS. 



effects almost exceeding belief. "In years peculiarly favourable to the 

 flowering of coniferous trees, vast clouds of pollen are borne on gentle 

 winds through the Pine forests and are often swept right beyond them so 

 that not only the seminiferous flowers, leaves and branches of the trees are 

 powdered over with the yellow pollen, but also the leaves of adjoining- 

 trees, and even the grasses and herbs of the meadows around. In tin 1 

 event of a thunder-storm at such a period, the pollen may be washed oft' 

 the plants and run together by the water as it flows over the ground, and 

 then, after the water has run off, streaks and patches of a yellow powder 

 arc left behind on the earth a phenomenon which has given rise on 

 various occasions to the statement that a fall of sulphurous rain has 

 taken place."* Many wel] -authenticated instances have been recorded : 

 Dr. Kngelmann found in the streets of St. Louis, after a rain-storm 

 from the south, in March when no Pines north of Louisiana were in 

 bloom, Pine pollen which must have come from the forests of P. 

 palustris on Red River, a distance of about 400 miles in a direct line. 

 At Bordeaux during the months of March and April these so-called 

 sulphur rains are not infrequent ; they are caused by clouds of pollen dust 

 wafted by westerly winds from the plantations of Pinus Pinaster which 

 cover the sand dunes of the Girond. "In Inverness-shire, a great shower 

 of the pollen of the Scots Pine took place in 1858 ; the ground was 

 covered by a layer of this substance in some places to a depth of half 

 an inch, and the deposit was noticed at places thirty-three miles apart. 

 The whole surface of the great lakes in Canada is not infrequently 

 covered by a thick scum of the same pollen. Similar occurrences have 

 been noticed in the forests of Norway and Lithuania." t 

 But the most remarkable part played by the pollen of Conifers 

 when dispersed by the wind and carried beyond the reach of the 

 seminiferous cones it was formed to fertilise is the nutrition it affords 

 as an organic constituent of the dust which supports the so-called 

 " red snow " a phenomenon that has always excited the wonder and 

 admiration of the naturalists who have studied it, even in a higher 

 degree than it has of the more general observers of Nature who 

 are unacquainted with its structure. 



"This red snow is now known to be a microscopic Alga of almost 

 ubiquitous distribution on the higher mountain ranges above the snow 

 line, a wonderful organism consisting of a cell wall furnished with a 

 pair of minute cilia, and with numerous chlorophyll grains coloured by 

 a red pigment thickly dispersed through the enclosed protoplasm ; it 

 thence belongs to a fascinating group of cryptogamic plants named 

 FLORIDB^: in reference to their brilliant colours. These minute plants 

 derive their nutrition from the carbonic dioxide absorbed by the 

 melting snow from the atmosphere and from the inorganic and organic 

 constituents of the dust distributed in it, of which the pollen 

 grains of Conifers forming the forests below the snow line are found 

 to be an ingredient, and whose occurrence in situations where one 

 might suppose all vital functions would be extinguished is scarcely less 

 remarkable than the simplicity of their structure and the richness of their 

 colour. Red snow is found on the Alps of Switzerland and the Tyrol, 



* Kerner's "Natural History of Plants," Oliver's Translation, Vol. II. p. 151. 

 f "Coal," by the Professors of the Yorkshire College, p. 24. 



