NO. 3 COMPARATIVE HISTOLOGY OF FEMTJE FOOTE 207 



Structure. — The external circumferential lamellae form a complete narrow 

 ring around the bone. The section is composed of well developed Haversian 

 systems closely packed together. Some are large, some small, and some are 

 irregular. Senile changes are frequent. 



The internal circumferential lamellae enclose the medullary canal. 



Type III, C, senile. 



EIGHT FEMUR OF A WHITE MALE. NO. 274, CR. MED. COLL. 



Pl. 35, Fig. 436. Syn. Tab. XI 



Antero-posterior diameter of bone, 30 mm. ; lateral, 35 mm. 



Antero-posterior diameter of medullary canal, 15 mm. ; lateral, 16 mm. 



Medullary index, 30%. 



Structxire. — The external circumferential lamellae are fragmentary. The 

 rest of the section is composed almost entirely of Haversian systems, many of 

 which are large in size and have large, irregularly shaped Haversian canals. 

 They are more numerous around the medullary canal than elsewhere. They 

 give to the section a general porous appearance when observed with the naked 

 eye. 



The internal circumferential lamellae form a narrow ring around the medul- 

 lary canal. 



Type III, C, senile. 



EIGHT FEMUR OF A WHITE MALE. NO. 275, CR. MED. COLL. 



Pl. 35, Pig. 437. Syn. Tab. XI 



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



Antero-posterior diameter of medullary canal, 19 mm.; lateral, 14 mm. 



The medullary canal is full. Medullary index, 50%. 



Structure. — The section is surrounded by a wide band of lamellaB, inter- 

 rupted by numerous Haversian systems of the (la) and (C) differentiations. 

 The central ring, about equal in width to tlie external lamellar band, is com- 

 posed of well developed Haversian systems, many of which are senile. 



A narrow ring of internal lamellae surrounds the medullary canal. 



Type I-III, la, C, senile. 



* LEFT FEMUR OF A WHITE MALE. NO. 276, CR. MED. COLL. 



Syn. Tab. XI 



Antero-posterior diameter of bone, 28 mm.; lateral, 33.5 mm. 

 Antero-posterior diameter of medullary canal, 26 mm. ; lateral, 17.5 mm. 

 Medullary index, 100%. 



