GROWTH OF THE SKELETON 



247 



ON THE WEIGHT OF THE CRANIUM— FRESH, ROOM-DRIED, AND 

 OVEN-DRIED (CRANIUM = SKULL WITHOUT MANDIBLES) 



The determinations have been made in this case in all three 

 conditions of moisture, as the weight of the cranium has signifi- 

 cance not only as a part of the skeleton, but also indirectly 

 as an index of cranial capacity and therefore of brain weight. 

 The data from the smoothed graphs are given in table 3 and the 

 graphs in chart 3. 



1 1 1 1 1 1 1 1 1 1 . g 



Chart 3 Absolute weight of the cranium — fresh, room-dried and oven-dried — 

 on body weight (albino rat). Table 3. 



• Fresh. A Room dried, x Oven dried. 



The form of the graphs does not call for special comment, 

 but a comparison of the initial values with those later in the 

 series shows that the cranium is increasing in weight p + only about 

 two-fifths of the rate of the entire skeleton. 



ON THE WEIGHTS OF THE DIVISIONS OF THE APPENDIC ILAR 



SKELETON 



Turning now to the two divisions of the appendicular skeleton, 

 it is possible to compare the shoulder-girdle plus appendages 

 with the pelvic girdle plus appendages, in their respective rela- 

 tions to the body weight. This has been done in table 4, and 

 both the absolute and relative values on body weight are given 

 in charts 4 and 5. A study of these data shows plainly that 



THE AMERICAN JOURNAL OF ANATOMY, VOL. 26, NO. 2 



