Experiments have also been performed on the eggs with a view of determining how far their vitality is influenced by high temperatures. We know that the scorching midsummer sun has no destructive influence on them, but these experiments prove that they are not influenced by a temperature only twenty degrees below the boiling point--actually a considerably higher temperature than is _necessary_ to properly cook a hen's egg. Let us now examine a number of eggs of different species, that we may note some of the many variations in form and colour. With regard to colour, we have already observed that the eggs of a few species are black; but more commonly they are much lighter--pearly white, green, yellow, and grey being of frequent occurrence. The great variety of form, however, will provide a vast amount of enjoyment to anyone who possesses a good magnifying lens or a small compound microscope. Some are globular, others oval; while many others represent cups, basins, and domes. Then we have miniature vases, flasks, bottles with short necks, and numerous figures that must remind a juvenile admirer of the sweet cakes and ornamental jellies that have so often gladdened his longing eyes. Again, the beautifully sculptured surfaces of a large number are even more striking than their general shapes. Some are regularly ribbed from top to bottom with parallel or radiating ridges, and at the same time marked with delicate transverse lines. Others are beautifully pitted or honeycombed, some ornamented with the most faithful representation of fine wicker-work, while a few are provided with a cap, more or less ornamental, that is raised by the young larva when about to see the world for the first time. A few of these beautiful forms are here illustrated and named, and another has already appeared on page 14, but an enthusiastic young naturalist may easily secure a variety of others for his own examination. [Illustration: FIG. 11.--EGG OF THE MEADOW BROWN BUTTERFLY.] [Illustration: FIG. 12.--EGG OF THE SPECKLED WOOD BUTTERFLY.] [Illustration: FIG. 13.--EGG OF THE VAPOURER MOTH.] It may be surmised from the accompanying illustrations that the form of the egg is always the same for any one species. This is really the case, and consequently an experienced entomologist can often decide on the name of the butterfly or moth that deposited a cluster of eggs he happens to find in his rambles and searchings; but in such decisions he is always greatly assisted by a knowledge of the food plants of the various insects, and sometimes also by the manner in which the eggs are arranged.