“The tissue of _Rhubarb_ is _very_ fibrous indeed. In fact, it is almost entirely made up of vessels. These are cells which have become tubes by the dividing cell-wall being absorbed. These vessels are very beautiful when seen under a microscope, for their walls are all thickened in some way, in order to make them strong enough to bear the weight of the leaf. Some are thickened by a spiral cord, which goes round and round the wall of the vessel. In some vessels this is quite tightly twisted round the wall, that is to say, the rings do not come far apart; in others it is quite loose and far apart. Another kind of thickening is by rings, which just go round the tube and are not joined to each other. Other vessels, again, have little knots in them like what there are in birch bark. “The _Potato_ tissue is mainly made up of starch, as it is one of the plant’s storehouses, and starch is one of the plant’s principal foods.” _Q._ Give a diagram of the eye, and explain how we see everything. (Book studied, Dr Schofield’s _Physiology for Schools_.) H. (aged 13):— “The eye can be likened to a camera, and the brain to the man behind the camera. The image enters at the hole, passes through the lens, is reflected on the plate, but the camera does not see, it is the man behind the camera who sees. In the same way, the image passes in at the pupil and through the lens, both sides of which are curved, and can be tightened or slackened according to the distance of the image. Then the image passes along the nerve of sight to the two bulbs in the brain which see. If you hold a rounded glass between a sheet of paper and the image at the right distance (for the glass cannot tighten or slacken like our lens), you will see the image reflected upside-down on the paper. This is the way the lens acts. There is a small yellow spot a little below the middle of the back of the eye; here the sight is more acute, and so, though we can see lots of things at one time, we can only look at one thing at a time. There is a blind spot where the nerve enters the eye (which shows that the nerve of sight itself is blind) so that some part of every image is lost, like a black dot punched in it. But we are so used to it that we cannot see it.” _Q._ Describe your favourite scene in _Waverley_. I. (aged 12½):—