In a contribution (Bartlett, 1971 a) to the Symposium on Statistical Ecology at Yale in 1969, I noted in my introductory remarks that that paper was not intended to be in any way a review of statistical techniques for analysing spatial patterns. My contribution to a conference at Sheffield in 1973 aimed, at least in part, to supply such a review and forms the basis of this monograph; but in these prefatory remarks I must still make clear what I decided to discuss, and what I have omitted. Broadly speaking, the coverage is that included in seminars and lectures I have given on this theme since...