Elementary Species in Nature 57 



treme variations in size, shape, color, taste, con- 

 sistency, and maturation period, indicating the 

 existence of separate races or elementary spe- 

 cies, with widely differing qualities. The earlier 

 varieties begin to ripen from August 10 to 20, 

 and a continuous supply can be had till Septem- 

 ber 10, while a few good varieties continue to 

 ripen till September 20. But even late in Octo- 

 ber some other types are still found maturing 

 their fruits. 



Exact studies were made of fruit and stone 

 variations, and their characteristics as to color, 

 weight, size, shape and consistency were fully 

 described. Similar variations have been ob- 

 served, as is well known, in the cultivated 

 plums. Fine blue-black fruits were seen on 

 some shrubs and purplish or yellow fruits on 

 others. Some exhibit a firmer texture and 

 others a more watery pulp. Even the stones 

 show differences which are suggestive of dis- 

 tinct races. 



Recently Mr. Luther Burbank of Santa Rosa, 

 California, has made use of the beach-plum to 

 produce useful new varieties. He observed 

 that it is a very hardy species, and never fails 

 to bear, growing under the most trying condi- 

 tions of dry and sandy, or of rocky and even of 

 heavy soil. The fruits of the wild shrubs are 

 utterly worthless for anything but preserving. 



