passages or tubes exist, while a connection is kept up with the pith of the tree by means of medullary rays. In one species of tree, known as the cork-oak, this is strongly developed.” It appears that Mr. Anderson enlivened his lecture by microscopic projections, for he goes on to say: “First I project on the screen a microscopic section of the wood of the cork tree. It is taken in a horizontal plane, and I ask you to notice the diversity of the structure and especially the presence of large tubes or pipes. I next exhibit a section taken in the same plane of the corky portion of the bark. You see the whole substance is made up of minute many-sided cells about 1/750 of an inch in diameter and about twice as long, the long way being disposed radically to the trunk. The walls of the cells are extremely thin and yet they are wonderfully impervious to liquids. Looked at by reflected light, bands of silvery light alternate with bands of comparative darkness, showing that the cells are built on end to end in regular order. The vertical section next exhibited shows a cross section of the cells like a minute honeycomb. In some specimens large crystals are found. These could not be distinguished from the detached elementary spindle-shaped cells, of which woody fiber is made up, were it not for the powerful means of analysis we have in polarized light. I need hardly explain that light passed through a Nicol’s prism becomes polarized, that is to say, the vibrations of the luminiferous ether are all reduced to vibrations in one plane and consequently if a second prism be interposed and placed at right angles to the first, the light will be unable to get through; but if we introduce between the crossed Nicol a substance capable of turning the plane of vibration again, then a certain light will pass. I have now projected on the screen the feeble light emerging from the crossed Nicol. I introduce the microscopic preparation of cork cells between them, and you see the crystals glowing with many colored lights on a dark ground. Minute though these cells are, they are very numerous and hard, and it is partly to them that is due the extraordinary rapidity with which cork blunts the cutting instruments used in shaping it.” In his research or experimentations Mr. Anderson was most deeply impressed with the elasticity of cork, and has the following to say upon his findings: “It would seem difficult to discover any new properties in a substance so familiar as cork, and yet it possesses qualities which distinguish it from all other solid or liquid bodies, namely, its power of altering its volume in a very marked degree in consequence of change of pressure. All liquids and solids are capable of cubical compression or extension, but to a very small extent; thus water is reduced in volume by only .00005 part by the pressure of one atmosphere. Liquid carbonic acid yields to pressure much more than any other fluid, but still the rate is very small.