408 ANEMOPHILOUS PLANTS. CHAP. X. 



(Typha) was 144 grains. Bucketfuls of pollen, chiefly 

 of Coniferae and Gramineae, have been swept off the 

 decks of vessels near the North American shore ; 

 and Mr. Eiley has seen the ground near St. Louis, 

 in Missouri, covered with pollen, as if sprinkled with 

 sulphur; and there was good reason to believe that 

 this had been transported from the pine-forests at 

 least 400 miles to the south. Kerner has seen the 

 snow-fields on the higher Alps similarly dusted ; and 

 Mr. Blackley found numerous pollen-grains, in one 

 instance 1200, adhering to sticky slides, which were 

 sent up to a height of from 500 to 1 000 feet by means 

 of a kite, and then uncovered by a special mechanism. 

 It is remarkable that in these experiments there 

 were on an average nineteen times as many pollen- 

 grains in the atmosphere at the higher than at the 

 lower levels.* Considering these facts, it is not so 

 surprising as it at first appears that all, or nearly all 

 the stigmas of anemophilous plants should receive 

 pollen brought to them by mere chance by the wind. 

 During the early part of summer every object is thus 

 dusted with pollen; for instance, I examined for 

 another purpose the labella of a large number of 

 flowers of the Fly Ophrys (which is rarely visited by 

 insects), and found on all very many pollen-grains of 

 other plants, which had been caught by their velvety 

 surfaces. 

 The extraordinary quantity and lightness of the 



* For Mr. HassaU's observa- Kerner, 'Die Schutzmittel des 



tions see ' Annals and Mag. of Pollens,' 1873, p. 6. This author 



Nat. Hist.' vol. viii. 1842, p. 108. has also seen a lake in the Tyrol 



In the ' North American Journal so covered with pollen, that the 



of Science,' Jan. 1842, there is an water no longer appeared blue, 



account of the pollen swept off Mr. Blackley, ' Experimental Re- 



the decks of a vessel. Riley, searches on Hay-fever,' 1873, 



' Fifth Report on the Noxious pp. 132, 141-152. 

 Insects of Missouri,' 1873, p. 86. 



