THE emotional life of spiders, so far as we can observe it as expressed in their actions, seems to be divided between sexual passion (including maternal affection) and the sterner feelings incidental to their fiercely predatory habits. But the emotions, although apparently few and simple in character, are exceedingly strong in force. In many species the male spider in conducting his courtship has to incur an amount of personal danger at the hands (and jaws) of his terrific spouse, which might well daunt the courage of a Leander. Ridiculously small and weak in build, the males of these species can only conduct the rites of marriage with their enormous and voracious brides by a process of active manoeuvring, which if unsuccessful is certain to cost them their lives. Yet their sexual emotions are so strong that, as proved by the continuance of the species, no amount of personal risk is sufficient to deter them from giving these emotions full play. There is no other case in the animal kingdom where courtship is attended with any approach to the gravity of danger that is here observable. Among many animals the males have to meet a certain amount of inconvenience from the coquetry or disinclination of the females; but here the coquetry and disinclination has passed into the hungry determination of a ferocious giantess. The case, therefore, because unique, is of interest from an evolutionary point of view. We can see a direct advantage to species from the danger incurred by males on account of mutual jealousy; for this, giving rise to what Mr. Darwin has called 'the law of battle,' must obviously be a constant source of the creation and the maintenance of specific proficiency; the law of battle determines that only the strongest and most courageous males shall breed. But the benefit to species is not so obvious where the danger of courtship arises from the side of the female. Still, that there must be some benefit is obvious, seeing that the whole structure of the male, if we take that of the female as the original type, has been greatly modified with reference to this danger: had the latter been wholly useless, either it would not have been allowed to arise, or the species must have become extinct. The only suggestion I can make to meet this aberrant case is that the courage and determination required of the male, besides being no doubt of use to him in other relations in life, may be of benefit to the species by instilling these qualities into the psychology both of his male and female descendants.