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1878.] On the Genealogy of Plants. 375 
that the Dicotyle may themselves be of heterogeneous origin, part 
of them being descendants of the Conifere, part, of the Guetacee, 
and part, of the Monocotyle. Should it ever become generally 
believed that the Dicoty/e are of multiple origin, the interest, 
now so great, in the true arrangement of the families of this class 
of plants would be greatly increased, and more satisfactory 
answers to many puzzling questions might be expected. 
Perhaps the least objectionable of all the theories advanced, as 
that which requires the least extreme or improbable assumptions, 
and affords the greatest relief from the dilemma, is that which 
maintains the two great co-ordinate branches or parallel ascend- 
ing series of the vegetable kingdom intact and independent from 
the’ most remote period to which they are traceable in the past 
history of the globe, and sees in the development of the endog- 
enous and exogenous Angiosperms at the summit of each, 
respectively, the simple attainment in both of one of the great 
ends of vegetable existence, without which the highest functions 
of plant life cannot be manifested. 
If we believe in the evolution of organic forms at all, we 
must accept that of vegetable forms, and if we are convinced 
that the higher plants are the descendants of lower ones, we 
ought by this time to have at least some provisional hypothesis 
as to the way in which this process of evolution has been go- 
ing on in the vegetable world. We should not go on accumu- 
lating facts forever without attempting to make any use of 
them. In this age, when the law of descent has reached, in 
zoology, its exact stage, the stage of prevision and prediction, 
it is certainly time that some of the operations of this law were 
recognized and studied in the cognate kingdom of plants. The 
utmost that can be objected to any present attempt to trace the 
genealogy of plants, is, that the precise truth has not been reached, 
and those who are really competent to raise this objection must 
be competent to present a nearer approximation to the truth, 
which is the very service which science most needs. It is, there- 
fore, with a full sense of the imperfection and inherent objection- 
ableness of the scheme, and an entire willingness to see it super- 
-seded by one which shall better satisfy all the facts of science, 
that the one here rudely sketched is submitted. Stripped of all 
its complicating conditions and qualifications, 
have been referred to and explained, this scheme of genéalogy | 
many of which | 5 
