It does seem clear from the above series of results that of the factors examined in their relation to rickets, etc., the only one of substantial importance is differences in the manner of feeding. The absence of definite association with overcrowding is, certainly, surprising, in spite of the fact that we realise how crude is the measure of this factor which we have had to adopt. If, as we suggest, the personal factor is not a very serious one, the above findings afford at least prima facie evidence of the truth of the assertions made previously, and are certainly sufficient to warrant the prosecution of further field enquiries, on this line, but having greater regard to the obtaining of the necessary information in a form more suitable for detailed analysis.In this section the influence of five possible factors on the weight of the child has been considered. No one of these can be shown to be of outstanding importance in this respect; but the efficiency of the mother shows the highest and most consistent relationship. Health of mother and those variations of feeding which are considered here as indiscretions have no appreciable influence on infant weight, but the remaining two variables, overcrowding and position of the infant in the family, seem to influence the weight of the child. In the case of overcrowding, the effect is small and only becomes substantial towards the end of the first year. Position of the infant in family, likewise, is of little moment; first and latest-born infants initially seem to have lower than average weights, but towards the end of the first year of life the weights of first-born infants tend to be over average, while those of infants born into already large families still show evidence of inferiority.