NUTRITIVE VALUE OF RAW AND BOILED MILK 197 



divergence between the curves, becoming somewhat increased 

 later and then diminishing fairly rapidly, until at a period rather 

 later than the sixth month, this difference has altogether disappeared. 



If reference be made to the tables given in Appendix D showing 

 the number of observations and the weights of the infants on each 

 day of life, it will be seen that the number of observations available 

 became larger shortly after the sixth week, and remained at a high 

 level during the whole period under consideration. The number 

 of observations is such as to eliminate any reasonable source of 

 error and to render the observations reliable. 



The weight curves of the two series show that the artificially 

 fed infant suffers from the disadvantage of its feeding for some 

 weeks after birth, when it begins to regain some of the lost ground, 

 and at about the sixth month it succeeds for the most part in 

 catching up, in weight at any rate, its breast-fed fellows. Evidently, 

 however, certain considerations must be borne in mind, and the 

 matter is not quite so simple as above outlined. 



In the first place it may be argued that the artificially-fed 

 children may be children of weaker parents, since the mother was 

 apparently unable to breast-feed her infant. Against this it may 

 be borne in mind that, speaking generally, the artificially-fed infants 

 are for the most part children of parents whose earnings are sufficient 

 to enable them to provide better hygienic surroundings for the 

 infant. This circumstance would probably to some extent mitigate 

 the disadvantage under which the child might suffer if the health 

 of its mother were unsatisfactory. In Berlin, if investigation of 

 the home circumstances showed that the parents could not afford to 

 buy milk, and it were necessary for any reason that the child should 

 be artificially fed, arrangements were made to supply the milk either 

 free or at a much reduced rate. In order to eliminate as far as 

 possible any source of error which might arise from these con- 

 siderations, a statistical investigation was undertaken of the 

 relationship of the nature of the food with the wages earned by 

 the father. 



(Note. The wages of the father were in all cases given on the 

 record charts and were available for use in these investigations, as well 

 as the other information in regard to the progress of the infant.) 



The result of the statistical investigation which is described 

 fully in the original paper, showed that the nature of the food 

 given, that is breast milk or boiled cows' milk, was more im- 

 portant to the infant than the wages of its father. In this con- 

 nection the reservation above mentioned as to the absence of 

 shortage of milk supply for the children, owing to the action of the 

 municipality, must be taken into consideration. 



The rate of growth of the infants in the two series was studied. 

 This was done in two ways. In the first place the percentage gain 

 shown by each series during each eight-day period was calculated. 

 Secondly, the rate at which growth progressed in each series 



