64 



FIELDS, GRAPHS, AND OTHER DATA ON FETAL GROWTH. 



of Hasse's cases fall in the most common weight interval of 3,250 to 3,500 grams, while 403, 

 or 17.8 per cent, of the Johns Hopkins series fall into the most common but somewhat lower 

 interval of 3,000 to 3,250 grams. Although the percentages in the most common weight 

 interval in these two series are practically alike, Hasse found 37.9 per cent of his cases in a 

 common length interval, as compared to 15.1 per cent in the Baltimore series. For this 

 difference I can offer no explanation, except that the fluctuations tend to increase with the 

 number of cases, although hardly to the degree here indicated, and that methods of measure- 

 ment may to some extent be responsible. Moreover, in contrast to Hasse, the percentages 

 in the common intervals of length and weight of our series differ but slightly — by only 2.7 

 per cent. As might be expected, this difference is to the advantage of the weight interval, 

 which is a comparatively larger interval and hence should include a relatively larger per- 

 centage of cases. The length interval of 1 cm. is manifestly only about 2 per cent of the 

 average birth-length, while the weight interval of 250 grams, on the other hand, is approxi- 

 mately 8 per cent of the average birth-weight. 



A graph similar to that in figure 4, giving the number of rases in each 250-gram 

 interval from 2,500 to 5,250 grams inclusive. Meyer 2,076 cases, Hasse 931 cases. 



Graphs for weight of Hennig and 

 Meyer. Hennig 100 cases, Meyer 

 229 cases. 



The marked difference in the length and weight curves is due to the fact that in the 

 case of weight several adjoining intervals contain almost as large a percentage of cases, but 

 this is not true in case of the length intervals. This difference is also very noticeable 

 indeed if the figures giving the number of cases in each centimeter length and each 250-gram 

 interval are arranged in column form. 



The curves in figure 2 give the number of deliveries in each 10-day interval from 150 to 

 340 days. Here the difference in position of the peak of the graph is due to the fact that 

 Hasler's graph was based on duration as estimated from conception, while my graph is 

 based on duration as estimated from the beginning of the last menstruation. Bearing this 

 in mind the correspondence is excellent. 



