STATING THE CASE. 



35 



and many other flowers do not possess petals — they 

 are fertihsed by the zvind. Every farmer knows the 

 necessity for dry, fairly windy weather, when '' the 

 corn is on the bloom," for then the pollen is carried 

 about. Every acre of wheat produces about 5 o lbs. 

 weight of pollen. If it happens to be wet weather, 

 a good deal of the pollen 

 is washed to the ground, 

 and never reaches the 

 'f)istils at all, so that they 

 cannot be fertilised. Un- 

 less they are fertilised 

 no seed-corn is produced. 

 The weight or produc- 

 tion of the grain crop 

 depends on the number 

 of the flowers in the 

 ears which are effectively 

 fertilised. 



When a pollen -grain 

 from one flower has been 

 conveyed to the upper 

 surface of the pistil of 

 another flower, it is held 

 there by a sticky matter 

 which exudes. The 

 pollen -grain begins to sprout, just as if it were a 

 seed, and buds forth a tube which has the power 

 of making its way right to the base of the pistil. 



Fig. 12. — Pollen-grains (highly magnified), 

 showing first the pollen - grain, then 

 the latter sprouting and at length 

 budding forth a pollen-tube. 



