54 MILK AND ITS HYGIENIC RELATIONS 



The conclusions which may be drawn appear to be : 



1. That human milk contains about three to four times as 

 much iron as cows' milk. 



2. That there is sufficient iron in human milk for the needs of 

 the infant. 



3. That the iron content of cows' milk cannot be increased by 

 feeding with iron compounds. 



Calcium. Much work has been done upon the calcium 

 content both of human and cows' milk, but the standpoint from 

 which the investigations have been undertaken are somewhat 

 different. In dealing with human milk, attention has been directed 

 towards ascertaining the amount of lime present, and endeavouring 

 to compare this amount with the calcium requirement of the 

 young child. It seemed possible that a study of the calcium 

 content of human milk might throw light upon the occurrence of 

 rickets in breast-fed children. 



In cows' milk the investigations on the general calcium content 

 have not been extensive ; efforts appear to have been directed 

 mainly towards the percentage distribution of calcium that 

 is, the amount present in organic and inorganic combination 

 respectively. 



The distribution of the calcium content of milk that is, its 

 combination with either organic or inorganic substances is not a 

 problem which affects the present work. The normal infant or 

 young animal can probably avail itself of the calcium present in 

 the milk, whatever the form of the calcium. 



The work upon the calcium content of human milk carried out 

 by the earlier authors has been carefully summarised by Bahrdt 

 and Edelstein (2) in 1910, and it will only be necessary to refer 

 anyone interested in the full details to the paper by these 

 authors. 



The work of Hunnaeus (1909) may be mentioned before con- 

 sidering that of Bahrdt and Edelstein. 



Hunnaeus studied the calcium content of human milk in relation 

 to the stage of lactation, and other points. He found the calcium 

 content for the same woman varied very little. 



1. In five samples of milk taken in the morning and evening, 

 the amount varied between 0*046 per cent, and 0*0351 per cent. 



2. In six samples of milk taken as first milk and as end milk, 

 the figures lay between 0*046 to 0*038 per cent., the content for 

 the first milk being rather higher than that for the end milk. 



3. Samples taken from twelve women in the first month of 

 lactation showed rather more variation, the figures varying from 

 0-0518 to 0*0332 per cent. 



4. No variation occurred in the total calcium output in the milk 

 of the same woman on different consecutive days, although in the 

 later months of lactation there is a tendency for the total amount 

 to decrease. This is shown in the following table : 



