J.D. Hooker, Introductory Essay to the Flora of Tasmania. 309 
should not only be the highest now existing, but have more 
highly differentiated vegetative organs than any subsequently 
appearing; and that the dicotyledonous embryo and pertect ex- 
ogenous wood with the highest specialized tissue known (the 
coniferous, with glandular tissue*), should have preceded the 
monocotyledonous embryo and endogenous wood in date of ap- 
pearance on the globe, are facts wholly opposed to the doctrine 
of progression, and they can only be set aside on the supposition 
that they are fragmentary evidence of a time further removed 
from that of the origin of vegetation than from the present day ; 
to which must be added the supposition that types of Lycopodt- 
ace, and a number of other orders and genera, as low as those 
now living, existed at that time also. 
8, Another point is the evidence,+ said to be established, of 
? E : : 
tity, of some of these with existing species. The changes in the 
level and contour of the different parts of the earth’s surface 
which have occurred since the period of the chalk, or even since 
that preceding the rise of the Alps, imply a very great amount 
2 sh difference between the past and present relations of sea an 
id and climate; and it is no doubt owing to these changes 
- that the Araucaric, which once inhabited England, are no longer 
found in the northern hemisphere, and that the Australian gen- 
ma which inhabited Europe at a period preceding the rise of the 
ps have since been expelled. 
84. Such facts, standing at the threshold of our knowledge of 
ge paleontology, should Jead us to expect that the prob- 
“ of distribution is an infinitely complicated one, and suggest 
© 1d that the mutations of the surface of our planet, which 
Teplace continents by oceans, and plains by mountains, may be 
oP cant measures of time when compared with the duration 
be! some existing genera and perhaps species of plants, for some 
: appear to have outlived the slow submersion of con- 
tinents, 
* The vexed nestion of the t ition of Gymnospermous plants in the Nat- 
une didtious sockentnt aaa as ede the view of species bein: 
iain 2 progressive evolution, In the haste to press the recen 
tion, the I vegetable impregnation and em 
°ductive organs themsel @ymnospermo 
detrated or wholly lost erg of ‘ er pee examination of the doctrines of progres- 
. ay ] , 
presented by these orga 
tui themselves is, in the “icine gate of science, a 
eat See fifth foot- v7 (1): I have there said of the supposed iden- 
tite ot-note of p. 307 (|): what sar 
the Australi nera applies to many of the other enumer- 
