188 QUARTERLY CHRONICLE OF MICROSCOPICAL SCIENCE. 



This being here very thin, the intra-cartilaginous bone there- 

 fore is soon involved in the process of absorption. Such 

 absorption-lacunae remain for many years in the superficial 

 layers of the intra-cartilaginous bone. In transverse sections 

 through the humerus of a human foetus, especially if they are 

 stained -with haematoxylin, this is quite clearly to be seen. 

 Such sections, if they are made through the upper extremity 

 of the diaphysis, show laterally a distinct periosteal cortex, 

 and on its external surface an apposition of bone-substance. 

 At the median side, however, this periosteal cortex is absent 

 altogether, and the periosteum is in immediate contact with in- 

 tra-cartilaginous bone, in which the residua of the trabeculse of 

 the cartilaginous matrix are brought out remarkably well by 

 heematoxylin — a fact first pointed out by Strelzoff himself. 

 At these points the surface of the int^acartilaginous bone 

 contains very numerous Howship's lacunar, and in them as 

 usual osteoclasts. Transverse sections through the tibia 

 below the condyles show exactly the same. Substantially 

 the same was found in the tibia of a male aged fifteen years. 



"2. Fo7'mation of the first vessels in bone, developed from 

 cartilage ; origin of the osteoblasts and osteoclasts. — In this 

 paragraph Kolliker confirms the asertion of Loven, Sharpey, 

 and especially of Gegenbaur, that the marrow of bones 

 which are preformed as cartilage, originates, in all its consti- 

 tuent elements, from the perichondrium or the periosteum 

 respectively. The circumstances that led Kolliker to this 

 conclvision are these : 



" [a) In the cartilage of the epiphyses and in the short bones 

 the well-known processes of the perichondrium, Avhich project 

 into the cartilage, and which contain, besides blood-vessels, a 

 fibrillar matrix with spherical and spindle-shaped cells, do 

 not develop from the cartilage (Virchow), but from the peri- 

 chondrium. The cartilage itself does not become dissolved, 

 as supposed, by the progressive growth of those processes, 

 but is simply pushed aside. 



" {b) In the diaphyses of the phalanges of the embryo of calf, 

 sheep, pig, and man it can be shown that after the appear- 

 ance of the first thin periosteal crust of true bone substance 

 and the first calcification of the inner cartilage, processes 

 grow from the osteogenetic layer of the periosteum, which 

 spread out gradually towards all sides, and penetrate into tlie 

 cavities of the cartilage-capsules. The tissue of which these 

 processes consist is similar to that of the perichondral pro- 

 cesses, previously mentioned, except that it is more loose, and 

 that it contains more spherical elements. From these latter 

 the osteoblasts and osteoclasts (myeloplaxes) take their origin. 



