140 T. H. BAST 



genetic buds into the areolae of Sharpey from the perichon- 

 drium. T. W. Todd, however, beUeves that the fibroblasts of 

 cartilage bone arise in situ. Thus he says: "Osteoblasts do 

 not enter skeletal tissue along the blood vessel's tracks, but 

 are fibroblasts or connective tissue cells which have undergone 

 certain characteristic modifications and may not have passed 

 through the chondroblast stage." This view is also held by 

 Macewen. 



The stages passed through by the fibroblast in becoming 

 an osteoblast, do not directly concern us, the transformation 

 of the osteoblast into a bone cell is the point of immediate 

 importance. According to current views the osteoblast de- 

 posits bone only on that surface which is in contact with bone 

 spicules. When one of these osteoblasts becomes aged, worn 

 out, or inactive it is gradually surrounded by the osseous prod- 

 uct of other osteoblasts which remain active. At this stage 

 the term osteoblast (bone former) no longer applies and the name 

 bone cell is used. Thus bone cells are passive protoplasmic 

 bodies lying in bone pockets called lacunae. It is to this cell 

 lying within the lacunae that we shall turn our attention. 



TECHNIQUE 



The material for this paper presented itself in an entirely 

 unlooked for manner. While investigating the glands of a dog's 

 nose the thin lamina of bone of the turbinates and the ethmoid 

 attracted attention. Curiosity led to a number of experiments 

 which proved interesting. After trying many stains and 

 manipulations in order to obtain differential preparations the 

 following procedure gave satisfactory results : 



1. Fix small pieces of thin bone in 95 per cent alcohol. 



2. Wash in water. 



3. Stain for 8-24 hours in a dilute aqueous solution of Gen- 

 tian Violet. (The stain should be diluted until it is transparent 

 when viewed in a test tube.) 



4. Dehydrate as rapidly as possible in 75 per cent, 95 per cent 

 and absolute alcohol. 



5. Clear in benzol. 



