56 Elementary Species 



produced and the time of flowering were vari- 

 able to a remarkable degree. 



Dr. Harshberger had the kindness to send me 

 some dried specimens of the most interesting of 

 these types. They show that the peculiarities 

 are individual, and that each specimen has its 

 own characters. It is very probable that a 

 comparative experimental study will prove the 

 existence of a large number of elementary spe- 

 cies, differing in many points; they will prob- 

 ably also show differences in the amount of 

 the active chemical substances, especially of 

 emetine, which is usually recorded as present in 

 about 1^, but which will undoubtedly be 

 found in larger quantities in some and in 

 smaller quantities in other elementary species. 

 In this way the close and careful distinction of 

 the really existing units might perhaps prove 

 of practical importance. 



Macfarlane has studied the beach plum or 

 Prunus maritima, which is abundant along the 

 coast regions of the Eastern States from Vir- 

 ginia to New Brunswick. It often covers areas 

 from two to two hundred acres in extent, some- 

 times to the exclusion of other plants. It is most 

 prolific on soft drifting sand near the sea or 

 along the shore, where it may at times be washed 

 with ocean spray. The fruits usually become 

 ripe about the middle of August, and show ex- 



