222 Macfarlanc—The Beach Plum, Viewed 
limited centers of plant distribution, types may originate 
apparently from no traceable environmental causes, which 
vary powerfully in the very parts—fruit and stone—that con- 
tribute to the perpetuation and distribution of the species. 
(c) Fruit Size and Shape-—The two smallest fruits 
observed, belonged to plants that differed in nearly every other 
respect, viz.: Nos. 1 and 12 of the above table. Both were 
spherical fruits that had a cross-measurement of II to 13 mm. 
Occasionally bushes of type 1 may be encountered in which the 
shape tends more toward the spheroid. Intermediate grada- 
tions can be traced from these to the largest, which was sphe- 
roidal in shape and measured 21 mm., but the most note- 
worthy in shape of its fruits was No. 3 of the table. Two 
bushes were observed, the fruit was oval in outline and 
measured 12 by 17 mm. The shape and size were surpris- 
ingly uniform over each plant, and indicated a fixed heredi- 
tary condition in the plant. 
As in our varieties of the cultivated plum, so in these a 
pronounced carpellary sutural groove may occur in some, 
only a faint trace of it in others, while in Nos. 4 and to of 
the table the groove is obliterated. 
(d, e) Fruit Taste and Consistence.—The numerous varia- 
tions shown, in both of these respects, by the cultivated 
plums of our day are well known. Similar variations are seen 
in the wild beach plum. Average fruits have what might be 
described as a slightly watery pulp, that is, instead of posses- 
sing the firm continuous pulp of our best plums, it here con- 
sists of pulpy tissue filled in between with softer, almost 
watery material that inclines to drip. This is true of the 
finest blue-black fruits of large size, such as No. 7 in the 
table, and even of the small blue-black types. The purplish- 
red and yellow fruits are of firmer texture, while No. 1 of the 
table has a hard, close pulp, that is small in quantity and poor 
in quality. 
