1878. ] On the Genealogy of Plants. 361 
I do not propose in this paper either to review the literature of 
this subject, which is already becoming voluminous, or to attempt, 
among the many conflicting theories advanced, to reconstruct the 
natural system; but shall seek rather, in the light both of the new 
facts and the new principles already accepted, to state some of | 
the objections to the received classification, and sketch, in its 
most general outlines, the form and direction which I conceive 
that the approaching reform is most likely to assume. 
Probably the most objectionable feature of the system of classi- 
fication proposed by Jussieu and still adhered to in nearly every 
systematic work on botany, is the position of the Gymnosperms. 
These constitute a sub-class of the Exogens and are made 
co-ordinate with the sub-class Angiosperms, which only embraces 
the Dicotyledons proper, or true flowering Exogens. 
This arrangement and terminology involves a number of grave 
inconsistencies. In the first place the so-called Endogens or 
monocotyledonous plants are as truly Angiosperms as are the 
plants to which that term has been thus specially applied, the 
pistil consisting in both cases of a closed ovary. The Gymno- 
sperms, therefore, in the present system are placed between the 
two great divisions of the Angiosperms and made to interrupt 
the natural series. The most casual observation, both of the 
foliage and the flowers, shows how awkward this position is, and 
indicates without closer scrutiny, that the Gymnosperms are out 
of place. Moreover, the enclosure of the germ is what chiefly 
` “distinguishes the pheenogamic from the cryptogamic series, and 
” 
the degree to which this is accomplished should mark the degree 
of advancement from the cryptogamic state. But we shall pres- 
ently look deeper into this phase of the question. 
In the second place, the reason assigned for the position of the 
Gymnosperms is the exogenous structure of their woody tissue. 
This argument might have some force if only the Conifere were 
embraced in the sub-class; but when we consider the Cycadacee, 
which equally belong there, a difficulty arises. Here the woody 
tissue assimilates almost altogether that of the endogenous palms 
or cryptogamic tree-ferns. 
Again, the wood of the Conifere is by no means identical with 
- that of the true Dicotyledons. It is destitute of the continuous 
vessels called ducts with their minutely porous joints, so charac- 
teristic of the former. The secondary wood consists, with the 
