_I have to thank Mr. John Murray for permission to reprint the article on Sleeping Sickness, and I am also greatly indebted to scientific colleagues for assistance in the survey of progress given in the second discourse. Amongst these I desire especially to mention Mr. Frederick Soddy, F.R.S., Prof. H. H. Turner, F.R.S., Prof. Sydney Vines, F.R.S., Mr. MacDougal of Oxford, and Prof. Sherrington, F.R.S. To Mr. Perceval Lowell I owe my thanks for permission to copy two of his drawings of Mars, and to the Royal Astronomical Society for the loan of the star-picture on p. 90._ E. RAY LANKESTER, _January, 1907_. ERRATUM. Page 98: first line of description beneath Fig. 16., _for_ Limnocodium _read_ Limnocnida. THE KINGDOM OF MAN CHAPTER I _NATURE’S INSURGENT SON_ 1. THE OUTLOOK. It has become more and more a matter of conviction to me--and I believe that I share that conviction with a large body of fellow students both in this country and other civilized states--that the time has arrived when the true relation of Nature to Man has been so clearly ascertained that it should be more generally known than is at present the case, and that this knowledge should form far more largely than it does at this moment, the object of human activity and endeavour,--that it should be, in fact, the guide of state-government, the trusted basis of the development of human communities. That it is not so already, that men should still allow their energies to run in other directions, appears to some of us a thing so monstrous, so injurious to the prosperity of our fellow men, that we must do what lies within our power to draw attention to the conditions and circumstances which attend this neglect, the evils arising from it, and the benefits which must follow from its abatement. 2. THE WORD ‘NATURE.’