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leaves thinner, stipules narrow and spines straight, or nearly so, 
often absent in stunted bushes. Seeing the extremes in an herba- 
rium, knowing nothing of the situation in which they grew, one 
would be strongly inclined to think he had two well-marked 
species with which to deal. On the other hand, however, could 
he but see the intermediate forms, their perfect intergradation, 
he could come to no other conclusion than that he had before 
him but one. 
Hybridization may be invoked as a factor in the production 
of variant forms, but so far this is only conjectural. When these 
occur, as they frequently do, blending the characters of supposed 
species, that they are hybrids is an easy inference ; and they may 
be so. The best presumptive evidence is sterility in otherwise 
healthy bushes. Watson, in his excellent monograph, A History 
and Revision of the Roses of North America,* speaking of Rosa 
lucida, Ehrh., says that the fruit is sometimes ‘“ oblong-ovate,” 
but attributes this deformity, with fewer seeds, to the work of in- 
sects. Dr. Torrey, in Flora of New York, states that a similar 
change is observed at times in the fruit of Rosa Carolina, L., and 
also ascribes it to insect work. With due deference to these 
acute observers, I am disposed to ask whether it is not probable 
that the cause at the bottom is not sterility from hybridizing, the 
insects taking advantage of the space made vacant by the absence 
of seed, and thus appearing to be the cause when in reality they 
are not? Iam led to this questioning by observing that most 
frequently this atypic form of hips is seen in bushes in which 
the characters of Rosa lucida and Rosa Carolina are blended. If 
this change depended de ovo on the work of insects, like changes 
in other species growing in the same locality should be expected, 
which, however, is rarely the case. 
The time of flowering is a valuable criterion whereby to judge 
whether different forms are in reality the same species or not. If 
they commence to bloom at the same time in the same situation, 
it is reasonable to suppose that they are the same. It is true that 
two or more good species might flower at exactly the same time, 
but the presumption is to the contrary. Caution therefore is 
Proceedings of the Amer, Acad, of Arts and Sciences, Vol. xx. 
