592 REPORT-—1905. 
WEDNESDAY, AUGUST 30. 
The following Papers and Reports were read :— 
1. Botanical Photographs as Aids to Ecological Research, 
By Professor F. E. Weiss, D.Sc., F.L.S. 
The impetus given to the study of plant-associations by Warming’s classical 
work on the ecological distribution of plants has been particularly noticeable in 
Great Britain, where quite a number of botanists have undertaken systematic 
surveys of the vegetation of various districts, and good progress has already been 
made in the botanical survey of Scotland and the North of England, There 
is no doubt, however, that the mapping of the vegetation of these regions, useful 
as it is, requires to be supplemented by a detailed study of the ecological factors 
governing the local distribution of plants, and this fact has not been lost sight of 
by those who have been engaged in the work. In this connection it is essential to 
obtain accurate records of the aspect and distribution of the vegetation at various 
altitudes, on different geological formations, and under varying conditions of 
drainage, illumination, moisture, &c. This can be done most efficiently by good 
photographs, and the recently established Committee for the survey and study of 
British vegetation, realising the necessity for such photographs, have decided to 
establish a collection of such ecological photographs in furtherance of their work. 
Some photographs of this nature are already included in the wider scheme for the 
collection and preservation of photographs of botanical interest established two 
years ago by the British Association, and it is to be hoped that the two collections 
will be made supplementary one to the other. The value of photography for work 
of this kind is undeniable. It has already been used with excellent results by 
Schimper in his ‘Plant Geography,’ and that such photographic representa- 
tions of plants are coming into favour for teaching purposes is attested by the 
success of Karsten and Schenk’s ‘ Vegetationsbilder,’ and by the excellent photo- 
graphic reproductions issued by Hansen as diagrams illustrating the geographical 
distribution of plants. The advance made by the use of such photographie repro- 
ductions for book- and class-illustration is evident on comparing the issues referred 
to with the illustrations of some of the older books dealing with kindred subjects. 
Not only does photography give the ‘most truthful representation of plant form, 
but it can be made to show the aspect of the surroundings to which any plant, or 
group of plants, has become adapted. It shows the relative abundance or sparse- 
ness of the vegetation in any given locality, and gives a clear idea of the features 
of any plant-association, exhibiting the dominant form, or forms. Of course, all 
these points cannot, as a rule, be clearly shown on one photograph, and it becomes 
therefore necessary in most cases to have several views. It is more particularly 
desirable to have a detailed photograph of each member of a plant-association, as 
well as of the association as a whole. 
Plant photography can, however, be usefully employed in the study of other 
subjects than geographical distribution. Photographs have already been in use 
for some time past for the representation of the results of plant-breeding where 
differences of form and habit are often very slight, and not easily represented by 
other than photographic means, Photographs are equally applicable to the repre- 
sentation of abnormal growths, whether pathological or teratological. On the 
Continent they have been used, too, in recording for different districts any trees of 
particular interest, either by reason of their great age or of any peculiarities of 
vrowth. This kind of work, due to the initiative of Dr. Conwentz, has resulted 
in some very beautiful publications by various Governments and public authorities, 
and their example might well be followed by local authorities and field clubs in 
Great Britain. 
Even for cryptogamic work photography has proved of great use, especially in 
such groups as the lichens, in which the species exhibit a great variety of habit. 
But in other groups, such as alge and liverworts particularly, considerable improye- 
ment may be made in the representations commonly found in botanical ook, 
