THE OSSEOUS SYSTEM. 



271 



other, mucli in the same waj that the laminae of the walls of the 1 

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



arjjer 



Fisr. 112. 



Fig-. 113. 



mg to a canal, and the collective thickness of the system formed bj 

 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 lamellie, 

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



Fio. 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 lamelltc ; b, 

 internal surface towards the medullary cavity, with the inner lamells; c, Haversian canals 

 in transverse section with their lamellar systems; rf, interstitial lamella?; c, lacunce 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 radiathig stria? in the 

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

 osseous substance; d, lacuna without visible rays. From a preparation by Dr. H. Mailer. 



* [The "interstitial lamina?" 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 



