Whilst very easily acted on by heat, starch-granules are very resistent to certain other reagents. Weak alkalies, in watery solution, readily attack them, but by treating portions of plants with caustic potash dissolved in strong spirit, the woody and other parts may be dissolved away; and after repeated washing with spirit the starch may be mounted. This, however, must never be in any glycerine medium, except that given on p. <a href=\"#Page_172">172</a>. * * * * * In Plate III. Fig. 1, may be seen a curious little drawing, which is a sketch of the laurel-leaf cut transversely, and showing the entire thickness of the leaf. Along the top may be seen the delicate layer of “varnish” with which the surface of the leaf is covered, and which serves to give to the foliage its peculiar polish. This varnish is nothing more than the translucent matter which binds all the cells together, and which is poured out very liberally upon the surface of the leaf. The lower part of this section exhibits the cells of which the leaf is built, and towards the left hand may be seen a cut end of one of the veins of the leaf, more rightly called a wood-cell. We will now examine a few examples of surface cells. Fig. 5 is a portion of epidermis stripped from a Capsicum pod, exhibiting the remains of the nuclei in the centre of each cell, together with the great thickening of the wall-cells and the numerous pores for the transmission of fluid. This is a very pretty specimen for the microscope, as it retains its bright red colour, and even in old and dried pods exhibits the characteristic markings. In the centre of the Plate may be seen a wheel-like arrangement of the peculiar cells found on the petals of six different flowers, all easily obtainable, and mounted without difficulty. Fig. 30 is the petal of a geranium (Pelargonium), a very common object on purchased slides. It is a most lovely subject for the microscope, whether it be examined with a low or a high power,--in the former instance exhibiting a most beautiful “stippling” of pink, white, and black, and in the latter showing the six-sided cells with their curious markings.