ENVIRONMENT 91 



each two years at the proper season to distribute 

 their seeds. The seeds of other pines do not re- 

 tain their vitahty and ability to grow even after 

 the third year. The Geyser pines produce cones 

 in great abundance in circles around the trunk 

 and branches when much younger than other 

 pines — sometimes when only two or three feet 

 in height. The cones of these pines remain 

 closed on the trees so persistently that the new 

 wood sometimes grows over them, surrounding 

 them completely, but the seeds, even in these 

 cases, remain in best growing condition after 

 their long imprisonment in the wood. The cones 

 never open to distribute the seed until a fire 

 sweeps over the land, when those which have 

 been gathering on the trees, perhaps for thirty 

 or forty years, immediately open and soon after 

 scatter the seed, from which the young pines 

 often come up as thick as grass on a lawn. Of 

 course some of these succumb to the crowding of 

 their neighbors, but what a wonderful adaptabil- 

 ity these pines have shown; a lesson which no 

 other pine has been obliged to learn. In learn- 

 ing these hard lessons which have become so 

 deeply fixed in heredity, innumerable individuals 

 have taken part, for time is generally the 

 chief factor, and they can be fixed only by 

 repetition. 



