NO. 3 COMPARATIVE HISTOLOGY OF FEMUR FOOTE 193 



LEFT FEMUR OF A WHITE MALE. NO. 161, MED. DEFT. NORTHWESTERN UNIV. 



Pl. 31, Fig. 398. Syn. Tab. X 



Antero-posterior diameter of bone, 28 mm.; lateral, 31 mm. 



Antero-posterior diameter of medullary canal, 12 mm.; lateral, 15 mm. 



The medullary canal is full. Medullary index, 26%. 



Structure. — The external lamellae are practically absent. The central ring 

 is composed of various forms of Haversian systems with considerable inter- 

 Haversiau lamellae, especially in tlie inner wall. This is the remains of the 

 horseshoe. Many senile changes are present. Near the posterior ridge the 

 systems are oval and assume a concentric arrangement. The internal lamellae 

 form a narrow ring around the medullary canal. 



Type III, C, senile. 



RIGHT FEMUR OF A WHITE MALE. NO. 153, MED. DEPT. NORTHWESTERN UNIV. 



Pl. 31, Fig. 399. Syn. Tab. X 



Antero-posterior diameter of bone, 27.5 mm.; lateral, 26 mm. 



Antero-posterior diameter of medullary canal, 14 mm.; lateral, 11 mm. 



The medullary canal is full. Medullary index, 27%. 



Structure. — A wide horseshoe band of lamellae extends around the external 

 border of the section and is interrupted by numerous crude Haversian systems 

 of the (la) differentiation and crossed by canals. The central ring is com- 

 posed of large, small, and irregular Haversian systems, some of which are 

 senile. The internal lamellae form a broken ring around the medullary canal. 



Type I-III, la, C, senile. 



RIGHT FEMUR OF A WHITE MALE. NO. 243, CR. MED. COLL. 



Pl. 31, Fig. 400. Syn. Tab. X 



Antero-posterior diameter of bone, 30 nmi. ; lateral, 27 mm. 



Antero-posterior diameter of medullary canal, 16 mm.; lateral, 14 mm. 



The medullary canal is full. Medullary index, 23%. 



Structure. — The section is surrounded for the most part by a wide horse- 

 shoe band of lamellae, interrupted fi-cqnently by Haversian systems of the (la) 

 differentiation. 



The central ring is composed of Hascrsian syslcms witli fragments of 

 lamella^ running between them in all directions. This is especially true in the 

 outer wall. A few senile systems appear. Internal circumferential lamclhi' 

 form a narrow ring around the medullary canal. 



Type I-III, la, C, senile. 



