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than before ; over the age of 15, females suffered rather more severely than males. Attention is drawn (see preceding section) to the fact that a similar age and sex incidence has been noted in different parts of the world in regard to threadworm infestation. The latter has, epidemiologically, some curious points of resemblance to poliomyelitis, and it is suggested that recent discoveries about its mode of spread may supply clues to some hitherto unexplained features of the more serious disease. The task of the investigator is to establish facts. It is not a primary object of this paper to suggest the manner in which its conclusions might be translated into practice. One could not help being impressed, however, with the emphasis which the findings throw on the role of the school-child in spreading infection and introducing it into the home—particularly the older schoolboy; on the likelihood of faecal organisms, rather than droplet infection, playing the major part in propagating the disease ; and on the supreme importance of personal hygiene over all possible general measures of control. With regard to these last, however, the chief point of practical importance which emerges is that a particular kind of public assembly is especially to be avoided in epidemic times —that is, any in which children are collected together, use closets in common, and take food. Day schools and children's parties are therefore much more dangerous than casual contact in trams, buses, shops, or in the streets. It is to be noted, however, that we have shown that by the time we are made aware of the presence of an epidemic the infection has already become widespread. School closure, therefore, unless it is prompt, can only be of limited value. That it definitely was of value in the present instance lam convinced. Experience of this measure in England or the United States of America has little interest for us in New Zealand, because conditions here are different from those in any other country. I doubt if the public in Britain would respond as well to the requirements of the health authorities as they did in Auckland, and there is no city in England whose average living conditions are at all comparable or which has such an abundance of private gardens and open spaces where children can enjoy the fresh air without coming into contact with others outside the family circle. When the schools reopened in Auckland, a note from the Health Department was read out to all classes warning the children (amongst other things) that they must be careful to wash their hands before lunch. When lunch-time came, in one school at least, some of the older boys were heard to say that " they weren't going to wash their hands — only sissies did that." This, as we have seen, is the group chiefly responsible for spreading the infection—and no wonder ! X. SUMMARY (а) A field investigation into an outbreak of poliomyelitis in Auckland in the summer of 1947-48 is described. (б) The object of the investigation was to study the background of the epidemic in the general population, to discover how it had commenced, and how much minor illness related to poliomyelitis had occurred (i) amongst household contacts, (ii) in other persons residing in the same neighbourhood, and (iii) in those parts of the urban area least affected by-the epidemic. (c) Conclusions reached have been detailed in the preceding section. A relationship was established between minor (" suspect ") illnesses and positive cases ; the ratio of " suspect " to positive cases at different age levels has been calculated, and an estimate is given of the extent to which the population as a whole was affected. Seasons are adduced for believing that, during an epidemic, mode of life and personal habits may be of more importance in determining the fate of the individual than previously acquired immunity. (d) It is suggested that indoor dust-borne infection, at school and in the home, may be important, and that the results of recent research into threadworm infestation may throw light on this factor.

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