As Mr Petersen points out in this study, since the war there has been a very strong belief in the Netherlands that emigration is necessary. Even those who never before occupied themselves with these matters now speak of the large natural increase, the overpopulation, and the lack of opportunities in the Netherlands. Thousands are considering the possibility of leaving their home land and creating a new existence for themselves overseas. It is a mistake to suppose, however, that these ideas stem from the special demographic and economic conditions that arose in the Netherlands since the war; the opposite is the case. From this point of view, there has never been less reason for emigrating during the past decades than in these postwar years. As far as the demographic situation is concerned, by 1930 the natural increase had decreased markedly as compared with the preceding decades, so that the number of young persons entering the labor market after the war has been relatively small. On the other hand, there have been more openings in industry and in other sectors of the economy than ever before, so that unemploy ment pretty much disappeared. Only in 1951 did it again become at all significant."

Professor Hofstee has collected together, in compact and highly readable form, some of the most important conclusions so far reached in the study of selective aspects of internal and external migration. Of still greater value, however, than this sum mary of findings, and more stimulating to those of us who are directly concerned with demographic research, are Professor Hofstee's comments on the undocumented hypotheses with which the literature of migration abounds, and his suggestions concern ing the kinds of questions to which objective answers are needed if effective progress is to be made in this branch of social studies. The study of migration has had a curiously unsatisfactory history. Statistics of migration developed as by-products of governmental policy and, even so, with scant regard to those ques tions on which light needed to be thrown if policy was to have a sound basis. And as, for long periods, internal movement was not considered a fit subject for policy, the statistics in that field tended to be even less useful. In many countries, net balances of movement by major administrative areas were the only indicators that could be obtained. No less important, however, as an expla nation of the unsatisfactory state of the subject is the fact that so much of non-governmental research has been piece-meal and un-coordinated - often of considerable interest in itself but, as is the case with sociology in general, not building up into a systematic structure."