HISTOLOGICAL DEMONSTRATIONS. 83 



b. Picro-carmine ( 322) gives fair results. It stains the 

 bone corpuscles, and to a less extent the matrix. Before 

 staining with this agent all chromic or picric acid should be 

 removed by washing the sections in water. 



c. Purpurine is strongly recommended by Ranvier as a 

 staining agent for the bone corpuscles, on account of its 

 staining them only. Chromic or picric acid is previously 

 washed out of the sections, and they are then placed in a 

 solution of purpurine ( 326) for twenty-four to forty-eight 

 hours. It does not, however, appear to show more than 

 picro-carmine does. 



Sections of softened bone unstained should be mounted 

 in rectified spirit or glycerine jelly ( 350) ; glycerine 

 renders them too transparent. If stained, they may be 

 mounted in Farrants' solution, glycerine, or glycerine jelly. 



121. Structure of Bone. Examine a T. S. un- 

 softened bone prepared as directed in 118. 



(L.) The compact and spongy bone. The Haversian 

 systems in the former, with a Haversian canal cut trans- 

 versely in or near the centre of each system. The lacunas 

 with their canaliculi. 



(H.) The lacunae usually more or less flattened. The 

 canaliculi dividing and anastomosing with those of neigh- 

 bouring lacunae, so as to form what is probably a system 

 of lymphatic channels. The canaliculi of the lacunae 

 nearest the Haversian canal open into it, and thus the 

 lymph can readily pass from the blood capillaries in the 

 canal into the canaliculi. The contents of the Haversian 

 canals and lacunae will be found in preparations of decalci- 

 fied bone. 



122. Examine a V. S. unsoftened long bone. (L.) The 

 Haversian canals mostly cut vertically. They anastomose, 

 and some may be found opening on the periosteal surface. 

 Others may be found passing into the spaces in the spongy 

 bone. The Haversian systems being divided vertically, the 

 concentric arrangement of their lacunae is of course not 

 here seen. 



123. T. S. softened long bone of cat. If the section is 

 unstained, examine it in dilute alcohol ( 284) for the 



