310 



PROCEEDINGS OF THE CANADIAN INSTITUTE. 



It is a question whether from the facts of development one is 

 entitled to lay such stress upon the presence of cartilage, and thus 

 to separate so distinctly the perichondral from the membrane bones. 

 I should prefer to have two classes of bone-formation (I.) that in 

 which the calcareous matter is first deposited in the centre of the 

 cartilage, and (II.) that in which it is not. In the first class 

 enchondral bone would be placed and in the second the other four. 

 But since such classification should indicate the ontogeny of the bone 

 as well as its histogenesis, since the preformation of a bone in carti- 

 lage is of great use in determining its homologies, the second class 

 should be subdivided. My classification would then be as follows : — 



I. Bones developing from ossificatory centre in the cartilage. 

 1. Endochondral bone. 

 II. Bones which do not develope from ossificatory centre in the cartilage. 



A. Bones preformed in cartilage : 



1. Exoperichondral (centrifugal). 



2. Endo-perichondral (centripetal). 



3. Cement bones which replace cartilage. 



B. Bones not preformed in cartilage : 



1. Membrane bones. 



2. Cement bones which do not replace cartilage. 



Guelph, February 25th, 1884. 



