STRUCTURE AND MULTIPLICATION OF BONE CELLS 145 



ethmoid bone of a dog, shows an unusual anastomosis between 

 the protoplasmic processes. It appears all the more unusual 

 because they are represented as seen under a shifting focus. 

 Normally many of the processes do anastomose but end blindly 

 as seen in the remaining figures. These mounts of entire bone 

 also make clear the fact that the processes do not lie in one plane 

 only, but that they radiate in all directions to anastomose with 

 the surrounding cells. 



•■b 



d. The cytoplasm 



The cell protoplasm is of a finely granular nature. ]\Iost 

 preparations show a lightly stained, less gra.nular cytoplasm 

 immediately surrounding the nucleus. External to this is an 

 area containing numerous coarse, highly refractive granules. 

 These large granules become fewer toward the periphery but 

 some of them can be found even in the larger protoplasmic 

 processes (fig. 3). There is no sign of lacunar spaces or empty 

 canaliculi but the granular cytoplasm is everywhere in contact 

 with the clear bony matrix, 



e. The yiucleus 



The nucleus is normally of an oval shape and is eccentrically 

 placed. Many of the nuclei are shaped differently but such 

 shapes depend on the stage or type of amitosis which they 

 represent. The nucleus is very rich in chromatin which is 

 grouped into smaller or larger masses and irregularly distributed. 



/. The centrosomes 



Centrosomes can be seen in many of the preparations. 

 Gentian violet is not a specific stain for these structures but 

 very good results are often obtained. Iron hematoxylin is a 

 more specific stain but it can not be used for this purpose 

 because it corrodes and stains bone. Further details includ- 

 ing their position will be considered later. 



