This volume contains the texts of the lectures presented at the scientific meetings of 9 May 1970 and 23 January 1971 of the Systeemgroep Nederland. This society was founded on 9 May 1970 to promote interdisciplinary scientific activity on basis of a systems approach. It has its seat in Utrecht. Officers for the year 1971: President: A. F. G. Hanken, Technische Hogeschool Twente, Enschede. Secretary: G. de Zeeuw, Department of Psychology, University of Amsterdam. Treasurer: R. F. Geyer, Foundation for Interuniversitary Social Research. SISWO, Amsterdam. All information about the society can be obtained from the Secretary. Although this volume is entirely devoted to the lectures of the scientific meetings, future issues, to be collected into yearly volumes, are open to individ ual contributors. For details cf. p. II The editor v ADDRESSES OF AUTHORS Buijs, B. G. F., Technische Hogeschool Twente, Postbox 217, Enschede. Griend, P. C. van de, Nederlandse Economische Hogeschool, Burg. Oudlaan 50, Rotterdam. Hanken, A. F. G., Technische Hogeschool Twente, Postbox 217, Enschede. Leeuw, A. C. J. de, Technische Hogeschool, Insulindelaan 2, Eindhoven. Maarschalk, C. G. D., Zomerluststraat 11, Haarlem. Mantz, M. R., Trompenbergerstraat 7, Hilversum. Meuwese, W., Technische Hogeschool, Insulindelaan 2, Eindhoven. Rootselaar, B. van, Landbouwhogeschool, Afdeling Wiskunde, De Dreijen 8, Wageningen. Wassink, E. C., Landbouwhogeschool, Afde1ing Plantenphysiologie, Gen. Foulkesweg 72, Wageningen.
