424 



STRUCTURE AND LIFE HISTORIES 



pollen-grains are, of course, blown hither and thither with 

 every breeze, and millions of them never reach a carpellate 

 cone. The writer once found an accumulation of pine 

 pollen in a desk drawer that had remained constantly 

 closed (but in the vicinity of a pine tree) during the 

 season of pollination. A microscopic examination of 



Fig. 314. — Shedding of pollen from a xoun- pine tree. Note the cloud 

 of pollen at the left, caused b}^ shaking the tree. 



dust from ledges, indoors and out, at the pollen season, 

 will usually disclose one or more pollen-grains of pines 

 and other species. 



377. Pollen and Coal-formation. — A microscopic ex- 

 amination of muck from the bottom of almost any in- 

 land lake will disclose the fact that it contains millions of 

 pollen-grains of various cone-bearing trees, and spores of 



