It seems to be the fate, however, of all supporters of new theories to run into extravagances. Darwin had to remind his enthusiastic disciples that Natural Selection could not create variations, and we may feel some confidence that Hering, were he alive, would urge his followers to bear in mind that memory cannot create a state of affairs which never existed. So far we may certainly say that these internal secretions do produce certain physical effects, some of them effects not to be suspected by the uninformed reader. There seems to be very good evidence that the growth of antlers in deer depends upon an internal secretion from the sex-gland and from the interstitial tissue of that gland; for it is apparently upon the secretions of this portion of the gland that the secondary sexual characters depend, and not merely these, but also the normal sexual instincts. And this takes us a stage further. The extreme claim is that all instincts, in fact all thoughts and operations, are in the last analysis chemical or chemico-physical. Let us examine this claim for a moment. The adrenals are two inconspicuous ductless bodies situated immediately above the kidneys. Not many years ago, when the present writer was a medical student, all that was known about these organs was that when stricken with a certain disease, known as Addison's disease from the name of its first describer, the unfortunate possessor of the diseased glands became of a more or less rich chocolate colour. To-day we know that the internal secretion of these organs is a very powerful styptic, and there is good reason to believe that a copious discharge accompanies an unusual exhibition of rage. When we are told things of this kind we must first of all remember that the adrenalin does not cause the rage, though it may produce its concomitant phenomena. If a man flies into a violent passion because someone has trodden upon his corns, and there is a copious flow of adrenalin from the glands, it is not that flow which has caused his rage. It may be the flow from the interstitial tissue of the sex-glands which engenders sexual feelings, but then those are almost wholly physical, and only in a very minor sense--if even if any true sense--psychical. Persons who take the extreme view have never yet suggested that there is a characteristic hormone connected with those psychical attributes alluded to in the chapter of the Corinthians recommended to our notice by Butler. In fact they seem to ignore all but the lower or vegetable characters when dealing with psychology from the chemico-physical point of view. Finally, we come again to the fatal and fundamental defect of this as of other "explanations"; it is an explanation "_within the system_," and therefore unphilosophical in so far as it fails to explain the facts through their ultimate or deepest reasons.