1 84 



PRACTICAL HISTOLOGY. 



[XIV. 



become embedded in the bone matrix they become bone-corpuscles. 

 This piece of bone is perforated by blood-vessels, which pass into 

 the primary medullary spaces in the hollowed-out cartilage. 



(e.) (H) Examine the several parts. Search for an osteoclast 

 lying in a little cavity Howship's lacuna and notice that while 

 the margins of the trabeculae, covered by recently-formed bone, 

 are stained of a deep red colour by the carmine, no such red stain 



Osteogenic tissue 

 Emloclionclral bone 



Blood-vessel 

 Perichondral bone 



Enlarged cartilage-capsules 



Enlarged cartilage-capsules. 

 ^7 Calcified cartilage in the form of 



Pointed processes projecting into 

 the 



Primary medullary spaces. 

 Perichondral bone. 



Fro. i 57 . Dorso-palmar Longitudinal Section of the Second Phalanx of the Finger of 

 a Four-Months Foetus. 



is seen where the osteoclast is embedded. It, in fact, is eroding 

 or eating away bone. 



3. Epiphysis and Epiphys'al Cartilage (H and L). Make 



longitudinal vertical sections of a young rabbit's femur or tibia 

 to show the cpiphysial cartilage. Stain it in picro-carmine and 

 mount in glycerine-jelly ; or, better still, double stnin it in hsema- 

 toxylin and picro-carmine or haematoxylin and eosin. In the last 

 case the cartilage will be blue, the rest red or copper-red. The 

 method of double staining is particularly valuable for the study 

 of bone development. 



(a.) (L) Observe the thin layer of encrusting cartilage on the 

 head of the bone (fig. 158, (7), and under it the cancellated bone 

 of the head of the tibia. This cartilage is continuous below 

 with 



(/>.) A broad layer of cartilage between what is to be the head 



