Fune 2, 1870] 
ON THE PROGRESS OF BOTANY DURING 1869 * 
i 
It had been my intention on the present occasion to have 
carried on the sketches of the general progress of biological 
science which I had attempted in 1862, 1864, 1866, and 1868 ; 
but I haye, from various causes, being unable to bestow so much 
time as usual to the preparation of my address, and feel obliged 
to confine myself to a few points connected with subjects of 
special interest to myself, which, within the last two or three 
years, haye made considerable advances. 
The most striking are, without doubt, the results obtained 
from the recent explorations of the deep-sea faunas, and from 
the inyestigation of the tertiary deposits of the Arctic regions, 
which, although affecting two very different branches of natural 
science, I here couple together, as tending both of them to eluci- 
date, in a remarkable degree, one of the most important among 
the disputed questions in biological history, the continuity of life 
through successive geological periods. 
An excellent general sketch of the first discovery and 
progressive investigation of animal life at the bottom of the 
sea at great depths, up to the close of the season of 1868, is 
given by Dr. Carpenter in the Proceedings of the Royal 
Society, vol. xvii. No. 107, for December 17, 1868; the results 
of the still more important expedition of the past year have 
as yet been only generally stated by Mr. Gwyn Jeffreys, in the 
numbers of NATURE for Dec. 2 and 9, 1869; and by Dr. 
Carpenter in a lecture to the Royal Institution, published in the 
numbers of Scéentific Opinion for March 23 and 30, and April 6 
and 13 of the present year ; and further details, as to the Madre- 
poraria, are given by Dr. Duncan in the Proceedings of the 
Royal Society, 1 vol. xviii., No. 118, for March 24 of the 
present year ; whilst, in Nortit America, the chief conclusions to 
be drawn from those researches into the deep-sea fauna are 
clearly and concisely enumerated by Prof. Verrill, in the number 
of Sidliman’s Fournal for January last, and some of the more 
detailed reports of the American explorations by Louis and 
Alexander Agassiz, and others, haye been published in the 
Bulletin of the Museum of Comparative Zoology at Harvard 
College, Nos. 6, 7, and 9to 13. For the knowledge of the data 
furnished by the Tertiary deposits of the Arctic regions we <r2 
indebted almost exclusively to the acute observations and able 
elucidations of Prof. O. Heer, in his ‘‘ Flora Vossilis}Arctica,” in 
his paper on the fossil plants collected by Mr. Whymper in 
North Greenland, published in the last part of the Philosophical 
Transactions for 1869, and in the as yet only short general 
sketch of the results of the Swedish Spitzbergen expeditions, 
contained in the Genevan Bidliothégue Universelle Archives 
Scientifigues for December 1869. 
It would be useless for me here to retrace, after Dr. Carpenter 
and Prof. Verrill, the outlines of the revolution which these 
marine discoveries have caused in the previously conceived 
theories, both as to the geographical distribution of marine 
animals, and the relative influences upon it of temperature and 
depth, and as to the actual temperature of the deep seas, or to 
enter into any details of the enormous additions thus made to our 
knowledge of the diversities of organic life ; and it would be still 
further from my province to consider the geological conclusions 
to be drawn from them. My object is more especially to point 
out how these respective dips into the early history of marine 
animals and of terrestrial forests have afforded the strongest 
evidence we have yet obtained, that apparently unlimited per- 
maneney and total change can go on side by side without requir- 
_ing for the latter any general catastrophe that should preclude 
the former. 
There was atime, as we learn, when our chalk-cliffs, now 
high and dry, were being formed at the bottom of the 
sea, by the gradual growth and decay of Globigerine 
and the animals that fed on them; amongst others, for 
instance, Ahizocrinus and .erebratulina Caput-serpentis ; and 
when the upheaval of the ground into an element where 
these animals could no longer live, arrested their progress in that 
direction, they had already spread over an area sufficiently 
extensive for some part of their race to maintain itself undis- 
turbed, and so on from that time to the present day, by gradual 
dispersion or migration, in one direction or another, the same 
Rhizocrinus and Terebvatulina haye always been in possession of 
some genial locality, where they have continued from generation 
* Address of G. Bentham, F.R.S,, President of the Linnean Society, read 
at the Anniversary Meeting, May 24, 1870, 
NATURE 
ep i 
to generation, and still continue, with Globigerinc: and other 
animals, forming chalk at the bottom of the sea, unchanged in 
structural character, and rigidly conservative in habits and mode 
of life through the vast geological periods they have witnessed. 
So also there was a time when the hill sides of Greenland and 
Spitzbergen, now enyeloped in never-melting ice and snows, 
were under a genial climate, clothed with forests, in which 
flourished “Zaxodium distichum (with Sequoie, Magnolie, and 
many others), and when these forests were destroyed by the 
general refrigeration, the Taxodium occupied an area extensive 
enough to include some districts in which it could still live and 
propagate ; and whatever vicissitudes it may have met with 
in some parts, or even in the whole, of its original area, 
it has, by gradual extension and migration, always found 
some spot where it has gone on and thriyen, and continued 
its race from generation to generation down to the present day, 
unchanged in character, and unmodified in its requirements. In 
both cases the permanent animals of the deep-sea bottom and 
the permanent trees of the terrestrial forests have witnessed a 
more or less partial or complete change in the races amongst 
which they were commingled. Some of these primitive asso- 
ciates, not endowed with the same means of dispersion, and con- 
fined to their original areas, were extinguished by the geological 
or climatological changes, and replaced by other races amongst 
which the permanent ones had penetrated, or by new immigrants 
from other areas; others again had spread like the permanent 
ones, but were less fitted for the new conditions in which they 
had become placed, and in the course of successive generations 
have been gradually modified by the Darwinian process of 
natural selection, the surviyors of the fittest only among their 
descendants. If, in after times, the upheaved sea-bottom 
becomes again submerged, the frozen land becomes again suited for 
vegetation, they are again respectively covered with marine animals 
or vegetable life, derived from more or less adjacent regions, and 
more or less different from that which they originally supported, 
in proportion to the lapse of time and extent of physical changes 
which had intervened. Thus it is that we can perfectly 
agree with Dr. Duncan, that “this persistence (of type and 
species through ages, whilst their surroundings were changed 
over and oyer again) does not indicate that there have not been 
sufficient physical and biological changes during its lasting to 
alter the face of all things enough to give geologists the right of 
asserting the succession of several periods 7’ but we can, at the 
same time, feel that Dr Carpenter is in one sense justified in the 
proposition, that we may be said to be still living in the Creta- 
ceous period. The chalk formation has been going on over some 
part of the North Atlantic sea-bed from its first commencement 
to the present day, in unbroken continuity and unchanged in 
character. 
If once we admit as demonstrated the coexistence of indefinite 
permanency, and of gradual or rapid change of different races in 
the same area and under the same physical conditions, accord- 
ing to their constitutional idiosyncrasies, and also that one and 
the same race may be permanent, or more or less changing, 
according to local climatological or other physical conditions 
in which it may be placed, we have removed one of the 
great obstacles to the investigation of the history of races, 
the apparent want of uniformity in the laws which regu- 
late the succession of forms. We may not only trace, 
with more confidence, such modifications of race through 
successive geological periods as Prof. Huxley has recently 
exhibited to us in respect of the horse, but we can understand 
more readily the absolute identity of certain species of plants 
inhabiting widely dissevered areas, of which the great majority 
of species are more or less different. One of the arguments 
brought forward against the community of origin of representa- 
tive species in distant regions, such as temperate Europe and the 
Australian Alps, the Arctic Circle and Antarctic America, the 
Eastern United States and Japan respectively,—an argument 
which long appeared to me to haye considerable weight, —was 
this ;—that if disseverance and subsequent isolation results 
necessarily in a gradual modification by natural selection, how is it 
that when allare subjected to the same influences, the descendants 
of some races have become almost generically distinct in the two 
regions, whilst others are universally acknowledged as congeners, 
but specifically distinct, and others again are only slight varieties 
or have remained absolutely identical? ‘To this we can now 
reply, with some confidence, that there is no more absolute 
uniformity in the results of natural selection than in any other of 
the phenomena of life. External influences act differently upon 
