228 Macfarlane—The Beach Plum, Viewed 
most of the types already described can be found in close 
proximity, at all of the localities already named, from Cape 
May Point in the South to Falmouth and Martha’s Vineyard 
in the North. This might lead us to suppose that in all these 
centers agencies were at work, that so acted on some primi- 
tive type or types, as to cause such to branch out into the 
varieties described. 
Before discussing this further, it may be well to adduce 
some evidence in favor of the ground already taken that No. 
I of our table or some closely related form represents a 
primitive ancestral type that has come down to us, and has 
been the starting point, in all probability in the past, of most 
if not all of the varieties described. In nearly all the natural 
orders of plants that contain succulent fruited genera, the 
species that have the largest and richest fruit pulp are the 
most highly evolved, since seed dispersion by animals is 
increasingly aided by increased succulence. We can likewise 
accept it as proven that the primitive fruits were dry and that 
increasing succulence indicates advancing specialization. But 
as with flowers, so with fruits. The most primitive are of a 
green or semi-green color. Type I would conform to such a 
requirement better than any of the others. The large amount 
of tannin in some varieties, particularly in specimen I, though 
it might prove to be protective against certain hurtful agents, 
seems rather to indicate a primitive condition, derived from a 
dry fruited type in which tannin is a frequent constituent. 
The practical disappearance of it from the finer fruits of the 
Beach Plum, and the abundance in them of sugar, favor the 
view that the varieties most rich in tannin are the most 
primitive forms. 
As regards the lateness of ripening of No I, and a few 
related examples, this does not seem to be a matter of special 
importance. It is well known that several late-maturing 
apples and pears rank among the choicest, sufficient proof this 
