714 



THE MICROSCOPE. 



Professor Quekett's paper in an early number of the 

 Micros. Soc. Trans, gave an 

 excellent account of the " In- 

 timate structure of Bone." To 

 this paper we are indebted 

 for the following microscopical 

 investigation of bone : 



Bone consists of a hard and 

 soft part ; the hard is com- 

 posed of carbonate, phosphate, 

 and fluate of lime, and of car- 

 bonate and phosphate of mag- 

 nesia, deposited in a cartila- 

 ginous or other matrix; whilst 

 the soft consists of that matrix, 

 and of the periosteum which 

 invests the outer surface of 

 the bone, and of the medullary 

 membrane which lines its in- 

 terior or medullary cavity, and 

 is continued into the minutest 

 pores. If we take for exami- 

 nation a long bone of one of 

 the extremities of the human 

 subject, or of any mammalian 

 animal, we shall find that the 

 bony substance, or shaft, is 

 slightly porous, or rather oc- 

 cupied, both on its external 

 and internal surfaces, by a 

 series of very minute canals, 

 which, from their having been 

 first described by our coun- 

 tryman Clopton Havers, are 



thlS the 



of small Wocfc dots. 



Fig. W.-A transverse section of tJ* , 



Hummus, or fore-arm lone, of a sian canals, and serve lor the 

 hffifc^Ha'M; canal*; transmission of blood-vessels 

 with a slight tendency to a con- into the interior of the bone. 



centric arrangement of bone-cells T /> ^-i 



around them The bone-ceils are If now a thin transverse sec- 



f 



and be examined by the micro- 



