268 POSTNATAL GROWTH OF HEART, KIDNEYS, LIVER, AND SPLEEN. 



passed by the boys at about the age of 14 years, after which there is an increasing 

 difference until maturity. 



The weight of the heart varies more with the size of the individual than with 

 age, sex, or race, and it may be taken as an index of the size and activity of the 

 individual, other things being equal. The weights given by Bardeen, Vierordt, 

 Kress and others were placed on charts similar to those of my own, and similar 

 differences were found, although the weights given by these authors were greater 

 than my own, due to a difference in the selection of material. If these charts are 

 analyzed it will be found that at almost every age, in both sexes and both races, 

 there is a group of small hearts and a group of large hearts. In the early years 

 there is no distinct line of demarcation for the two groups, no zone where there is 

 complete absence of the heart weights; but after the age of 14 years such a zone 

 appears, and when the age of 17 years is reached there are no heart weights between 

 225 and 250 grams in my records. 



The cause of death was equally divided between acute and chronic disease in 

 both large and small hearts during the early ages; but at the age of 17 years there 

 are more large hearts among the acute cases and more small ones among the chronic 

 cases. The stature does not appear to alter materially the heart weight, since in 

 acute cases with large hearts the stature was about the same as in chronic cases 

 with small hearts; while in chronic cases with large hearts the stature was 6 cm. 

 less than that of acute cases with small hearts. 



The type of the individual seems to affect the heart weight, as, even after 

 discarding cases supposably influenced by disease, there still remain two groups, 

 large and small. The same is true when only accident cases are tabulated. The 

 largest hearts are found in cases of pneumonia, and the smallest in cancer and 

 tuberculosis. Not all of the large hearts, however, are found in pneumonia cases, 

 nor do all the small hearts occur among the wasting diseases. In the former it 

 might be inferred that the physique, the nourishment, or the disease has caused the 

 excessive size, but there seems to be little evidence that pneumonia causes any 

 considerable increase in the weight of the heart; therefore, the large size of the 

 organ may be attributed to the type of individual. In wasting diseases there is 

 loss of weight in the heart, but a part of the excessive smallness may also be attrib- 

 uted to the type. The meso-phylomorph is susceptible to cardio- vascular, renal, and 

 acute diseases, especially pneumonia ; the hyper-phylomorph to nervous, alimentary, 

 and wasting diseases, as already pointed out by me (1912). 



An average may be nothing more than a mean between two types, and the 

 individual may be of greater value in a study of this kind than a mass of averages. 



LIVER. 



At 2 months the liver weighs little more than at birth, after which there appear 

 to be three periods of rapid growth; the first from 3 to 12 months, the second from 

 2 to 8 years, and the third from 14 years to maturity. There is a decrease in the 

 increment of growth in each consecutive period from the first to the third. The 



