NO. 3 



COMPARATIVE HISTOLOGY OF FEMUE FOOTE 



213 



The central ring was composed of large, small, and irregularly shaped Ha- 

 versian systems and inter-Haversian lamellae. In some systems the Haversian 

 canals were very large and irregular, and in the others they were normal in 

 size. The lacunae were oval. In some portions of the section, large, irregu- 

 larly shaped spaces were present. The internal circumferential lamellae formed 

 a narrow ring around the medullary canal. 



Type III, C. 



XVI. HISTOLOGICAL EXAMINATION OF TWO ENTIEE 



HUMAN FEMORA 



1. Left Femur, 41 Cm. Long, No. 300, Cr. Med. Coll. 



This bone was cut into pieces 2.5 cm. in length, and a cross-section of each 

 piece was examined microscopically. The first section was made through the 

 equatorial diameter of the head, the second through the middle of the neck, the 

 third through the lesser trochanter, and the following sections through the shaft 

 and lower extremity. 



head 



This section was a circle with a diameter of 44 mm. It was surrounded 

 by an enclosing envelope of bone 0.5 mm. in thickness and composed of lamella? 

 with round and oval lacunae and rather infrequent canaliculi. 



The remainder of the section was made up of cancellous bone, the meshes 

 of which were filled with marrow. In the central portion of the section the 

 cancellous bone was much heavier than elsewhere. The walls of the meshes 

 were composed of lamellae with oval and long lacunae and radiated from the 

 center toward the periphery. No Haversian systems were found. 



NECK 



Antero-posterior diameter of bone, 33 mm. ; lateral, 27 mm. 



This section was surrounded by an envelope of bone, varying in thickness 

 from 1 mm. in the anterior to 3 mm. in the posterior wall. It was composed of 

 lamellae with oval lacunas and bushy canaliculi, interrupted by a few Haversian 

 systems. 



The remainder of the section was made up of cancellous bone, heavier in 

 the posterior than it was in the anterior wall, and having a radiating direction 

 from the posterior toward the anterior boundary of the section. The cancellous 

 bone, as a whole, was considerably denser than it was in the head and was 

 composed of lamellae, interrupted by a few crude Haversian systems. 



