NO. 3 



COMPARATIVE HISTOLOGY OF FEMUR FOOTE 



187 



LEFT FEMUR OF A WHITE MALE, AGE 50. NO. 10, MED. DEPT. NORTHWESTERN UNIV. 



Pl. 29, Fig. 380. Syn. Tab. X 



Antero-posterior diameter of bone, 30 rnm. ; lateral, 31.5 mm. 

 Antero-posterior diameter of medullary canal, 13 mm. ; lateral, 12 mm. 

 The medullary canal is full. Medullary index, 20%. 



Structure. — The external circumferential lamellae appear only in short frag- 

 ments. The central ring is composed of large, small, and irregular Haversian 

 systems with many senile changes. The internal circumferential lamellae form 

 a narrow ring around the medullary canal. 



Type III, C, senile. 



FEMUR OF A SENILE WHITE AMERICAN FEMALE, AGE 52. NO. 227876, U. S. NAT. MUS. 



Pl. 29, Pig. 381. Syn. Tab. X 



Antero-posterior diameter of bone, 22 mm. ; lateral, 25 mm. 

 Antero-posterior diameter of medullary canal, 13.5 mm.; lateral, 12 mm. 

 The medullary canal is full. Medullary index, 42%. 



There is a difference of eight years between the senile femora of figures 381 

 and 382. The two femora have about the same external diameter, but figure 381 

 has an index of 42%, and figure 382, 74%. 



Structure. — Femur (fig. 381) is of a slightly lower type of structure than 

 figure 382. This may be seen by the concentric arrangement of the oblong Ha- 

 versian systems of the inner wall. The external circumferential lamellae are 

 fragmentary. The central ring is composed of large and small Haversian sys- 

 tems in different stages of senility. A few are normal; that is, their Haversian 

 canals are about the usual size. Some have large Haversian canals and crescent- 

 shaped lamellae; some have large canals and narrow rings of granular lamellae; 

 some have large canals and perfectly black, opaque rings or crescents around 

 them; and some are entirely gone. 



The internal circumferential lamella? are fragmentary. 



Type III, C, senile. 



FEMUR OF A SENILE WHITE FEMALE, AG K 60. No. 227880, U. S. NAT. MUS. 



Pl. 29, Fig. 382. Syn. Tab. X 



Antero-posterior diameter of hone, 24 mm.; lateral, 25 mm. 



Antero-posterior diameter of medullary canal, 10 mm.; Lateral, 16 mm. 



Cancellous bone is present in places. The bone is extremely soft, light, and 

 1 hiii-walled. The medullary canal is relatively large. In the wall of the bone 

 are large, irregularly shaped spaces. 



The medullary canal is full. Medullary index, 74%. 



