456 



C. R. BARDEEN 



and that based on normal weight runs between 0.5 and 0.55 per 

 cent of the body weight for most groups in both the males and 

 females but averages higher in the males. 



At and immediately following birth most investigators have 

 found that the heart is relatively large. If, however, the weight 

 of the membranes at birth are included the proportional weight 

 given above holds approximately true. 



Thus Thoma estimates the normal average weight of the new 

 born at 3.96 K. including membranes but not including the amniotic 

 fluid and at 3.35 K. including the membranes. The heart he 

 estimates at 0.532 per cent of the body weight if the membranes 

 are included, at 0.625 per cent if they are not included. 



The following table (table 9) from Miiller indicates that 

 similar relations prevail during the latter part of foetal life. 



TABLE 9 

 Data from W. Miiller on the relative weight of the heart in foetuses 



From the data given above we conclude that fifty-five hun- 

 dredths per cent of the body weight approximates closely the 

 normal relative proportions of the heart weight in males at all 

 ages except at and immediately following birth and that in fe- 

 males the heart is slightly lighter, about fifty-three hundredths 

 per cent of body weight. In our tables we have not, however, 

 attempted to plot separate curves for males and females. The 

 estimates of heart weight given in tables A and B arc based upon 

 the assumption that the weight of the heart is 0.55 per cent of 

 the body weight. In estimating the relative weight at birth 

 the weight of the foetal membranes is included in the body 

 weight. 



