508 SCIENCE. 
cussion with Section K (Botany) on sym- 
biotic fermentation, in which several of the 
French visitors took part, was of much in- 
terest. Professor Marshall Ward, in open- 
ing the discussion, after considering the 
conditions under which symbiosis existed 
both in the vegetable and animal kingdoms, 
illustrating his views with such examples 
as that of the dual organism of lichens in 
which alga and fungus were the contributory 
organisms, passed to the more special sub- 
ject of symbiotic fermentation. In sym- 
biotic rermentations the one organism, such 
as a mould, appeared to prepare the way for 
the action of a subsequent agent, such as 
yeast; and the preparation of Japanese 
saké, or rice wine, is a typical example of 
this dual effect. The discussion which fol- 
lowed it is hoped has led to a more exact 
recognition of the divisions and relations of 
symbiotic changes which may serve to de- 
velop the study of the subject. 
Professor Dewar’s important discoveries 
relating to the solidification of hydrogen 
will be noticed subsequently. Colonel 
Waterhouse contributed a note on a re- 
markable result he has observed on the ex- 
posure of metallic silver to light; a visible 
image results on the exposed plate after 
prolonged exposure, but the effect may be 
got in a very much shorter space of time by 
the development of the latent image that is 
produced. The industrial application of 
what was probably a similar action was re- 
ferred to by Sir W. Roberts-Austen. Al- 
though the papers on organic chemistry 
were of a technical character, the discus- 
sions, reports, and individual contributions 
in this branch of the science aroused much 
interest, and special importance is to be at- 
tached to a paper by Mr. W. J. Pope, on the 
influence of solvents upon the optical activ- 
ity of organic compounds. 
The chemists present at Dover will always 
look back upon the meeting with a special 
appreciation of the able address delivered 
[N. S. Von. X. No. 250. 
by the President of the Section, Dr. Horace 
T. Brown. The subject of the fixation of 
carbon by plants is a common meeting 
ground for the chemist, physicist and biolo- 
gist. After reference to the accustomed 
view that the higher plants derive the whole 
of the carbon which goes to build up their 
tissues from the carbonic acid of the atmos- 
phere, Dr. Brown reviewed the work that 
has been done to show that extra-atmos- 
pherie sources of carbon may exist, and 
detailed his own experiments on the intake 
of carbon dioxide by plants, showing that 
this is directly proportional to the tension 
of the gas. 
Sir Archibald Geike’s presidential ad- 
dress before the Section of Geology which 
was given on the occasion of the visit of 
the French Association is printed below. 
The list of papers in geology was, as us- 
ual, a full one, so that, especially during 
the earlier days of the meeting, the time 
for discussion was limited. The subjects 
dealt with ranged over the whole of the 
wide field included in geological science, 
without any particular division being not- 
ably prominent. In stratigraphical as well 
as in economic geology the most important 
papers were those dealing with the coal- 
fields, and from their additional local inter- 
est those of Mr. R. Etheridge, F.R.S., and 
Professor W. Boyd Dawkins, attracted es- 
pecial attention. Mr. Etheridge treated 
the relations existing between the Franco- 
Belgian coalfield and those of Southwestern 
Britain, with the object of proving that the 
recent discoveries in Kent indicated the ex- 
istence of a chain of concealed coal-basins 
connecting the two regions. Professor 
Boyd Dawkins, while pursuing the same 
general argument and recapitulating the 
history of the discoveries in Kent, gave a 
brief description of the borings at present 
in progress under his superintendence at 
Ropersole, Ottinge, Hothfield, Old Soar, 
near Tonbridge, and Penshurst. At pres- 
