138 C. M. Jackson. 



piled by Vierordt, however, show that this figure is open to question 

 and that the ratio is quite variable. If the difference is due to the 

 asymmetry of the heart, we should naturally expect it to be less in 

 the adult, where the heart is relatively smaller. 



Liver. 



In the youngest specimen in which the liver was measured (11 

 mm., Table IV), it formed 4.85 per cent of the total body volume. At 

 the beginning in the 1st month it is of course relatively smaller. As 

 indicated by the curve in Fig. 3 (Table V), it increases to its max- 

 imum relative size during the 2d and 3d months. At this time 

 individual specimens may reach 10 per cent (cf. Table IV and V), 

 the average being about 7.5 per cent of the total body. During the 

 4th month, however, the liver drops in relative size to an average of 

 a little more than 5 per cent. This average is maintained through- 

 out the succeeding fetal months, although there is considerable indi- 

 vidual variation. In 145 full-term still-born cases, the average was 

 5.05 per cent; while in 101 live-born it was 5.23 per cent. Vierordt 

 estimates that the liver forms 4.57 per cent of the total body weight 

 in the new-born and 2.75 per cent in the adult. 



Pancreas. 



The pancreas is at first relatively small (cf. Tables IV and V), 

 forming in a specimen of the 6th week (1.7 cm.) .032 per cent of the 

 entire body volume. ''^ From the 4th month onward, the pancreas 

 remains fairly constant in relative size, averaging about .1 per cent 

 of the entire body. In 37 full-term still-born, the average was .105 

 per cent. In 90 born alive the average was .145 per cent of the 

 total body weight. Vierordt gives .11 per cent of the total body 

 weight for the pancreas in the newborn, and .15 per cent for the adult. 



Spleen. 

 As indicated by the curve of groAvth in Fig. 4 (also Tables 4 and 



'The case recorded by Welcker (45), in which the pancreas formed .45 per 

 cent of the total body weight, is either erroneous or an abnormality. 



