90 



BONE. 



Fig. 58. 









■O 



M 



4\». 



Fig. 53. — Portion of a Nodulated Later of Bone-Tissue from near the surface 

 OP the Shaft of a Decalcified IIfjierus. 



At one side shreds of fibrous lamellee are seen ia the figure, 

 diameters. 



]\[a-nified 300 



Ossified cartilage is found on tlie articular ends of adult bones, 

 lying underneath the natural cartilage of the joint, both in the move- 

 able articulations and in symphyses, and is in fact the deeper part of 

 the cartilage which has been encroached upon by the calcifying process. 



border such as often bounds a series of Haversian rings. Now, in the decalcified rib, it is 

 easy to peel off the inner from the outer layers, and the detached surface of the former 

 shows a number of oval eminences, some with one, othei-s with two, three, or more lacuna; 

 in their substance ; whilst what was the contiguous surface of the outer layers has exca- 

 vations that correspond. Again, in the grinding tooth of the horse, the surface of the 

 crusta petrosa which is contiguous to the dentine or to the enamel, is marked over with 

 spheroidal bodies having, in decalcified specimens, very much the appearance represented 

 in Fig. 53, but most of them with one or more lacuna-like cavities within. They 

 look very like distinct globules, and were described by Ozennak as calcified cells contain- 

 ing lacunic ; but on carefully viewing the decalcified layer in profile-sections and otherwise, 

 I am led to the conclusion that they are mammillary elevations of the surface, continuous 

 by their (sometimes contracted) bases with the general substance. The enamel is destroyed 

 in the decalcification, but the surface of the dentine of the cervix and root from which the 

 mammillated layer of crusta petrosa has been detached, is found to be excavated in a 

 manner to correspond with it ; an an-angement well calculated to secure their mutual 

 connection, [w. s. ] 



