In our sense of hearing we can only appreciate up to 40,000 vibrations in a second as a musical sound, whereas, with Light and other electrical phenomena, as we shall see in a later View, we can appreciate sympathetic frequencies of not only many millions, but indeed millions of millions in a second, and yet it is possible that, in the sense (of insects) we are now examining of life appreciating life, we may be in the presence of frequencies as far removed from light as light is from sound. If, then, we may follow the analogy from our highest senses, we seem to get a clear explanation of the mystery of insect discrimination. The insect, in her then state, could have no pleasure in the presence of certain plants, their modes of frequency being out of sympathy with that particular Insect Life, and, it may be conceived that, not only is there no inducement for the insect to alight on that plant, but that even in its near proximity that insect would feel discomfort or restlessness; when, however, a plant is reached which is near akin to the one required, less antipathy or unrest would be felt, and, when the true species of plant is reached, all would be harmony, pleasure, and rest, the functions of Insect Life would be vivified, and its life-work accomplished under the influences of sympathetic action. I have made several other investigations on this subject, but I must only give one more to illustrate the higher form of Animal Life appreciating Animal Life. There is a large class of insects, called Ichneumonidae, which lay their eggs in the bodies of caterpillars, and, as in the case of a moth laying its egg on the special food plant upon which its caterpillar can feed, so does each species of these insects unerringly lay its eggs in the body of a particular kind of caterpillar. It must be a wonderful sense which can enable an Ichneumon Fly to do this; it has never seen that caterpillar before, as the egg, from which its own caterpillar was hatched, was laid inside the body of one of those caterpillars, and the caterpillar upon which it fed had been eaten up and disappeared at least six months before the Ichneumon Fly had even made its way out of its own cocoon; and yet this insect is not only forced, by some mysterious power, to lay its egg in the body of a caterpillar, but there is only one species which will serve its purpose, and it has to hunt up this particular caterpillar from among thousands of other different species.