THE OSSEOUS SYSTEM. 



271 



other, much in the same way that the laminae of the walls of the larger 

 vessels are continuous with each other. The number of lamellae belong- 



Fijr. H2. 



ing to a canal, and the collective thickness of the system formed by 

 them varies not inconsiderably, and bears no constant relation to the 

 size of the canal, as is the case to some extent in the vessels ; small 

 canals, therefore, are not unfrequently surrounded by numerous lamellae, 

 and larger ones by but few.* In general, it may be said that the largest 



FIG. 112. Segment of a transverse section of a human metacarpal bone, treated with oil 

 of turpentine: a, external surface of the bone, with the exterior fundamental lamellae; 6, 

 internal surface towards the medullary cavity, with the inner lamella- 5 e, Haversian canals 

 in transverse section with their lamellar systems; d, interstitial lamellae; e, lacunae and 

 processes. Magnified 90 diameters. 



FIG. 113. Portion of a transverse section of the shaft of the humerus, magnified 350 dia- 

 meters, treated with oil of turpentine : a, Haversian canals ; 6, their lamellar systems, each 

 lamella presenting a more transparent and more opaque portion, with radiating striae in the 

 latter; c, darker lines, which probably indicate greater intermissions in the deposition of the 

 osseous substance ; rf, lacunae without visible rays. From a preparation by Dr. H. Miiller. 



* [The "interstitial laminae" are the remains of Haversian systems, the larger parts of 

 which have been removed by absorption to form new spaces. The irregular outline of the 



