JANUARY 26, 1912] 
as to the relation between the paleozoic and the 
present representatives; from Hquisetales, showing 
the recent development of knowledge in reference 
to the paleozoic forms; from VFilicales, showing 
the disappearance of the paleozoic assemblage once 
called ferns, and the development of knowledge in 
reference to Palswo-Marattiaceze and Priniofilices; 
and especially from Gymnosperms, showing the 
remarkable reconstruction of the phylogeny of 
that group. 
The great problem of paleobotany to-day is the 
history of angiosperms. Having perfected a 
weapon in the attack upon gymnosperms, it re- 
mains for the paleobotanist who is a vascular 
anatomist to uncover the origin of our greatest 
group, with its comparatively brief history. The 
origin is probably recorded in the Mesozoic, and 
we wish to see the significant structures, and not 
guess at external form, and much less guess at 
purely hypothetical connections. To this great 
task paleobotany is turning. We have had the 
guesses; and I am confident that presently we will 
have the facts. . 
2. Morphology: EDWARD C. JEFFREY. 
The often perfect condition of preservation of 
plant fossils and the comparatively unbroken 
series, which they present, from the remotest 
times to the present, has been of the greatest 
importance for the modern development of plant 
morphology. It is now clearly recognized that the 
doctrine of recapitulation, far from being solely 
exemplified by zoologice types, is much more clearly 
and certainly deducible from the historical and 
developmental study of plants, which in this as in 
so many other respects, show themselves more ad- 
yantageous for evolutionary studies than animals. 
It is clear likewise from the studies of the past 
decade, or decade and a half, that external mor- 
phology, even that of the reproductive organs, is 
of comparatively slight importance in connection 
with the doctrine of descent or its practical appli- 
cation to the natural system. Applied to the 
internal structures, the doctrine of recapitulation 
has many and striking illustrations in plants living 
and extinct. The correlation of paleobotany with 
internal morphology has shown, moreover, that the 
investigation of reversions is a very profitable 
direction of scientific exploitation. In addition to 
exemplifying recapitulation and reversion, plants 
further present another law, which is for the most 
part not apparent in animals. It has been shown, 
namely, that of the separate organs of the plant, 
the stem is most progressive and that root and leaf 
SCIENCE 
149 
lag behind in evolutionary development. As a 
consequence it is often possible to discover the 
structures of a remote geologic past in the roots 
or leaves of plants now living. In the principles 
of the recapitulation, reversion and retention of 
ancestral characters, we have as it were the three 
fundamental R’s of morphological science, by the 
aid of which we are now for the first time in the 
position to begin the construction of a natural 
system. 
3. Heology: ARTHUR HOLLICK. 
Plant ecology is that branch of botany which 
comprises the study of the interrelations of plants 
and their relations to environment. As a distinct 
science it is practically a product of the present 
generation, and the term has only been recognized 
in common usage within the past twenty-five years 
or so. 
The relation of paleobotany to botany, in con- 
nection with ecology, is mostly concerned with 
the problems of phytogeography. Paleobotany 
has supplied the explanations of many puzzling 
facts in regard to endemic floras; the occurrence 
of some genus or species only in certain widely 
separated regions of the earth, and the geographic 
isolation or limitation of others. Most of the 
phenomena of plant distribution in general at the 
present time would have no logical or adequate 
explanation but for the facts which have been 
revealed by the study of fossil plants and their 
distribution in the past. 
Among the many striking instances in such con- 
nection may be mentioned the explanations which 
paleobotany has given in regard to the endemic 
floras of Australia and other regions; the distribu- 
tion of such genera as Nelumbo and Liriodendron ; 
and the geographic isolation of Sequoia, Taz- 
odium, Ginkgo and other genera. 
In tracing the facts of the ancestry, former 
distribution and extinction of species and genera 
paleobotany has demonstrated that there is no 
necessity for invoking the aid of inadequate and 
unsatisfactory theories of migration in recent 
times, or the origin of a genus, de novo, in two 
widely separated regions, in order to account for 
some of the puzzling phenomena of modern phyto- 
geography. 
Following are abstracts of the papers presented 
at the scientific sessions: 
The Connective between Conidia of Penicillium: 
CHARLES THOM, U. S. Department of Agricul- 
ture. 
References to a ‘‘connectiye’’ (Briicke, Dis- 
