NO. 3 COMPABATIVE HISTOLOGY OF FEMUR FOOTE 183 



XV. MAN— MODERN WHITE 

 General Character of the P'emur 



The femora of the white race vary in shape to a marked degree. The med- 

 ullary canals occupy central, eccentric, and oblicjue positions. They are filled 

 with cancellous bone and marrow. The medullary surfaces are verj^ uneven. 

 The average medullary index is 35.8%. 



The type of structure varies from the third to the first and third. A great 

 many first and third type combinations are found in the various femora, and 

 the proportions of the first to the third type vary greatly. In some, it forms 

 a narrow surrounding band ; in others, the band increases in thickness until it 

 forms a quarter, third, half, or more than half of the wliole section; in still 

 others, it remains as a background of inter-Haversian lamellae. 



Detailed Examination 



femuk of a white male, no. 1629, u. s. nat. mus. 



Pl. 28, Fig. 373. Stn. Tab. X 



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



Antero-posterior diameter of medullary canal, 18 mm.; lateral, 17 mm. 



The medullary canal is full. Medullary index, 64%. 



Structure. — The external circumferential lamellfe form a very narrow ring- 

 around the section. Beginning a little to the inner side of the posterior ridge 

 and extending around the inner wall, beneath the external circumferential la- 

 mellae, is a narrow band of elliptical Haversian systems in cross-section. They 

 disappear as they approach tJie anterior wall. These structures are the re- 

 mains of the lamellfp and laminae seen so frequently in lower bones in the 

 same situation. Tlie middle ring of the section is composed of well developed 

 Haversian systems witli many communicating canals. The medullarj^ canal is 

 surrounded by a narrow ring of internal circumferential lamellas. The lacunae 

 and canaliculi are generally well developed. 



Type III, C. 



right femur of a white female. no. 147, MED. DEPT. NORTHWESTERN UNIV. 



Pl. 28, Fig. 373. Stn. Tab. X 



Antero-posterior diameter of bone, 33.5 mm. ; lateral, 32 mm. 

 Antero-posterior diameter of medullary canal, 19 mm.; lateral, 18.5 mm. 

 The medullary canal is surrounded by cancellous bone and is full. Medul- 

 lary index, 49%. 



13 



