224 Macfarlane—The Beach Plum, Viewed 
fruits. These mature from about August 10 on to the first week 
in September. Meanwhile the blue and blue-black, also the 
yellow varieties are coming forward, and give a succession of 
fruits from about August 18 to September 10. These again 
are followed by the small purplish-blue types, which ripen 
from about September 1 to 20. Finally, during the latter 
part of September and on to October 15, the medium-sized 
and small greenish-purple varieties ripen. These last seldom 
seem to attain the consistency—even in October when they 
fall—that we call ripeness. They are then decidedly firm in the 
flesh, and abound in tannin and acid constituents. 
(g) Variations in Fruit Stones—Darwin has drawn attention 
to, and has figured, varieties of the fruit stone of the cultivated 
plum.’ Though nothing has been observed in the beach plum 
that would compare with these, the differences are nevertheless 
suggestive. We may at once compare two rather extreme 
cases presented under Nos. 7 and 12 of the table. The 
former are oval, compressed in shape, are slightly rough and 
have a well-marked ridge that traverses one side and ends in 
a slight beak. The color is a dull crimson-red, the weight 
is .60 gram, and in relation to the pulp the stone is of 
cling-stone variety. The stones of No. 12 are of nearly spheri- 
cal shape, smooth and have only a faint indication of a ridge 
The color is a clear liquid yellow, the weight is .28 gm. and 
the pulp is entirely free from the stone. 
A COMPARISON OF THE BEACH PLUM WITH THE CULTIVATED 
PLUM AND Economic SUGGESTIONS ARISING THEREFROM. 
It seemed advisable during the progress of the present 
inquiry to institute a comparison between fruits of the beach 
plum and those of the garden plum. Authorities differ as to 
the wild parentage of the latter, but most agree that Prunus 
1¢¢ Variation of Animals and Plants,’’ Vol. I, p. 366. 
