Measles may be said to be nearly endemic in communities of children by reason of the regularity of its appearance at certain seasons of the year, and its peculiar partiality for definite age periods. Amongst the diseases of childhood it is conspicuous at times for its great mortality where associated with conditions of poverty and overcrowding. The small, spasmodic outbreaks which occur amongst an urban population may be said to be cyclical, and depending on the arrival of a number of children

more »

... t the susceptible age period. These localized epidemics are not in themselves of importance from the point of severity or complication; the attack is generally mild and the healthy child does not suffer from complications or resulting ill effects. The seasonal outbreak of measles of a low type of virulence is a different disease from that witnessed at times in the fulminating epidemics. In these the manifestation is of a wide and rapidly spreading nature, and its potentialities for immediate and remote physical mischief to the child, are much increased. The infecting agent seems to become aggravated as the cases increase in number, complications become constant and severe, instead of occasional and mild, and the tendency to serious sequelae is much enhanced. The mortality at these times is sometimes very high, particularly in institu¬ tions for children (15 to 35 per cent., Holt) ; on the other hand, a lower rate pertains in homes where the necessity for keeping a number of children of susceptible age in close association does not exist (4 to 6 per cent., Holt). During the years 1910 and 1911 outbreaks of measles of an excep¬ tional nature occurred amongst the emigrant children arriving in the port of New York. It was believed that an account of these eases would be of interest as possessing certain unusual features of their own, as well as from the large number under observation at the Hoffman Island Isolation Hospital during that period. For the proper appreciation of the factors underlying the occurrence among a certain class of an epidemic disease of exceptional severity, there should be first considered the physical condition of the individual, including also the nature of his environment, before and at the time of attack; the number of cases among a susceptible community and the