246 British Association Notes and Comments. 
has crystalline properties and is formed of packets of elongated 
molecules between which are planes of weakness. The fibre 
can be split up at these planes into fibrils. This is an essential 
pre -tanning process since it increases the capillary space 
through which the colloidal tannins can diffuse and makes the 
polar groups of the protein accessible to the tan. Collagen 
carries positively and negatively charged polar groups, and 
collagen fibres contain both bound and free water. Tanning 
consists in conferring chemical and physical stability on the 
collagen fibre by the suppression of the active groups and the 
elimination of water. 
PLANT STRUCTURE IN COAL. 
Prof. G. Hickling and Mr. C. E. Marshall told us that 
improvements in the technique of section-cutting and 
photography have made it possible to show that coal consists 
largely of plant -remains in which the details of the original 
structure are preserved with remarkable perfection. This 
detail, in some respects, far exceeds that which can be observed 
in the familiar calcified or silicified petrifactions or coal-balls, 
since in the coal most of the original substance of the plant 
remains, while in the petrifaction it has been replaced. By 
the study of isolated sheets of bark and portions of wood which 
are preserved as coal in the coal-measure shales the micro - 
structure of the plants can be studied in relation to their 
external form. The bark-structures of Lepidodendron, 
Bothrodendron and Sigillaria have been so studied, as well as 
certain woods. In certain cases it appears possible to demon- 
strate conclusively that the existing coal consists in part of 
the original plant -substance and in part of additional organic 
material which has been absorbed by the plant after death. 
STUART GEOGRAPHY. 
Prof. E. G. R. Taylor stated : — The economic problems of 
England three centuries ago, as they are discussed in the 
literature of the period, are strikingly similar to those dis- 
cussed in newspapers to-day. Over-population, the decay of 
rural life, urbanisation, unemployment, the burden imposed 
by high wages and rising prices on the upkeep of great estates, 
the ruin of the roads by heavy traffic for which they were not 
designed, the dangerous depletion of timber supplies, ‘ unfair 
foreign competition in the fishing industry, free trade and 
the balance of trade, the need for improvement of internal 
waterways, for the control of flood-waters, for the reclamation 
of fens and marshes, for the improvement of methods of 
husbandry — all these had their geographical aspects. 
The Naturalist 
