378 



THE MICROSCOPE. 



there is no superficial stalactite-like bulging of globules, it is only in 

 dry specimens that that is seen. Now, if such a specimen be steeped in 

 dilute hydrochloric acid, so as to remove all the earthy matters, the glo- 

 bules instantly vanish, and the dentine where they were seen assumes the 

 same aspect as that where they were not seen. No other change is pro- 

 duced. The existence of the globules, therefore, seems dependent upon 

 the presence of earthy material." * 



BONE. 



The elements of bone are lamellae and small corpuscles ; the latter 

 are possibly merely spaces between the former, in which is deposited 

 the earthy substance. The lamellse have for their basis cartilaginous 

 substance combined with earthy matter, or salts. These salts are 

 chemically combined with the organic basis. Acid dissolves only the 

 earthy salts, and leaves the organic basis of the same form as the bone 

 itself. The lamellse are homogeneous throughout like the intercellular 

 substance of cartilage, but chemically it is different, being resolved by 

 boiling in water into cotta, whereas cartilage is resolved into chondrin. 



1 2 



fig. 179. 



A transverse section of the human clavicle, or collar-bone, magnified 95 diameters ; 

 which exhibits the Haversian canals, the concentric laminae, and the concentric 

 arrangement of bone-cells around them. Some of the Haversian canals are white, 

 others black : the latter are filled with a deposit of opaque matter, used in the 

 grinding and polishing the section. When viewed under a lower power, they 

 appear to be only a series of small black dots, as shown in No. 2. 



Professor Quekett has given, in the Microscopical /Society's Trans- 

 * James A. Salter, M.B., Quarterly Journal of Microscopical Science, July 1853. 



