STRUCTURE AND MULTIPLICATION OF BONE CELLS 147 



followed by degeneration. This latter interpretation is in ac- 

 cord with Haour's statement that many bone cells degenerate 

 to form phosphoric acid which is essential for the deposition of 

 bone. 



LITERATURE AND DISCUSSION OF THE BONE CELL 



In the study of bone two types of preparations have been 

 employed in the past, namely, decalcified and ground bone. 

 Embryonic bone has been cut without decalcification but the 

 study of such preparations has apparently failed to contribute 

 anything to the knowledge of bone cells. For the study of the 

 bone cells the ground bone method is of little use except to show 

 where the cells were. The method upon which is based our 

 present knowledge of the bone cell is the decalcification and 

 section method. It is upon this decalcification method that 

 the following accounts are based. 



In the textbook of Histology by Lewis and Stohr, the following 

 statement is made: 



Active osteoblasts tend to be cuboidal or columnar, but as bone 

 production ceases they become quite flat. They form bone only along 

 that surface which is applied to the matrix. As the strand of bone 

 grows broader through their activity, it encloses here and there an 

 osteoblast, which thus becomes a bone cell (fig. 72). Apparently 

 bone cells do not divide, and if they produce matrix, thus becoming more 

 widely separated from each other, it is only to a slight extent and in 

 young bones; the}^ are therefore quite inactive. Each bone cell occu- 

 pies a space in the matrix, called as in cartilage, a lacuna, but unlike 

 the lacunae of cartilage those in bone are connected by numerous delicate 

 canals, the canaliculi. In ordinary specimens the canaliculi are visible 

 only as they enter the lacunae, which are thus made to appear stellate. 

 The matrix around the lacunae resists strong hydrochloric acid which 

 destroys the ordinary matrix, and so may be isolated in the form of 

 'bone corpuscles.' The 'corpuscles' correspond with the capsules 

 of cartilage, which may be isolated in the same way. The bone cells 

 nearly fill the lacunae and send out very slender processes into the 

 canaliculi. These may anastomose with the processes of neighboring 

 cells, as can be seen in the embrj^o, but it is doubtful if this condition 

 is retained in the adult. The processes, moreover, are so fine that 

 ordinarily they are invisible. 



Jordan makes the following statement: 



