856 



OSSEOUS TISSUE. 



increased if a little acid be added to the sec- 

 tion ; caustic alkali will produce a similar 

 effect. The intercellular tissue having become 

 granular, the parietes of the corpuscles next 

 undergo a similar change, and the central 

 nucleus or cavity can no longer be identified. 

 The accession of granules to the parietes of the 

 corpuscles constitutes the second stage of the 

 process of ossification. 



The third stage is an action of a different 

 nature, and is fulfilled in the absorption of the 

 osseous matter interposed between the cells, 

 and also of that portion of the ossified cells 

 which lay in contact with the intercellular 

 tissue of the columns. 



By this change, the column, once composed 

 of closed cells, is converted into a tube marked 

 by numerous indentations corresponding in 

 number to the cells which entered into its 

 formation, there being a contraction at the 

 points of junction between the cells. The 

 tube so formed, supposing this condition to be 

 permanent, would have closed ends, and the 

 length would be determined by the ends of 

 the columns of cells from which it was formed. 

 (See/g. 462.) 



These elongated tubes, I believe with the 

 authors of " The Physiological Anatomy," to 

 be the Haversian canals in their rudimentary 

 state. They do not, however, retain this form 

 of tubes with closed ends, but like individual 

 cells become perforated and communicate 

 with other tubes similarly formed ; but as these 

 do not follow each other in straight lines, the 

 openings are formed at the sides of the tubes 

 instead of their ends, so that these commu- 

 nications are at angles with the tubes. These 

 and other openings which are formed between 

 the cells or tubes lying parallel to each other are 

 those Haversian canals in their rudimentary 

 state which traverse bone at right angles to its 

 length, and form anastomoses with the longi- 

 tudinal Haversian canals, which in bone are by 

 far the most numerous. 



In the tubes no trace is left of the central 

 nucleus or cavity of the original cartilage cor- 

 puscle; they contain, however, small spheri- 

 cal bodies composed of very minute granules. 

 These are transparent and resemble in appear- 

 ance those peculiar globules found in the blood 

 and commonly designated lymph globules. 

 (Soe fig. 462). 



They are very numerous, and, indeed, al- 

 most fill the cavity. They have a red tinge, and 

 constitute almost entirely the mass of red 

 matter found in the interior of all recently 

 formed and forming bone. These bodies were 

 described by Dr. Todd and Mr. Bowman, and 

 they suppose them to be concerned in the 

 developement of vessels, since up to this period 

 of ossification no bloodvessels exist in the 

 forming tissue, but make their appearance so 

 soon as the tubes become pervious. 



If a tiansverse section be made of bone 

 in this stage of its formation, there will be 

 no difficulty in recognising, first, the ossified 

 intercellular tissue, then the ossified parietes 

 of the once cartilage corpuscle, which, being 



Fig. 462. 



now the lining of the tube, will eventually 



be the external lamina of an Haversian system ; 



and, lastly, the granular globules contained in 



the tubes. 



The last point for consideration in the de- 

 velopement of bone is 

 the formation of the 

 bone-cells. Several re- 

 cent authors consider 

 the cells to be formed 

 from the nucleus of the 

 cartilage corpuscle ; I 

 have not been able to 

 confirm their state- 

 ments, but have been 

 led to entertain a diffe- 



rent opinion of their 

 origin. The formation 

 of tubes having been 

 Section of the tubes farmed comp leted, the inner 



i... ji.. 77 r if 



layer formed from the 



by the cells. 



a, intercellular tissue . . . 



ossified ; b, ossified pari- parietes of the corpus- 

 etes of the corpuscles ; c, 

 granular lobules con- 



tained in the tubes. 



cle is at first thin, and, 

 could it be withdrawn 

 entire, would look like 

 a tube formed by the junction of a number of 

 hollow beads. Partial separation may, however, 

 be produced, as seen in fig. 463. This state of 

 alternate dilatation and contraction seen in the 

 tube at its first formation is soon lost, and the 

 tube becomes of nearly equal diameter through- 

 out from the filling up of the dilatations by the 

 deposition of osseous matter in the usual gra- 

 nular form. But in this filling up of the dila- 

 tations small cells are left, and these are the 

 bone-cells in the rudimentary condition, and 

 form the outer layer of cells in the Haversian 

 system. (See fig. 463.) At first it is difficult 

 p. . fl ~ to distinguish the tubes 



of the bone-cells, but 

 if a section be taken 

 nearthe perfectedbone, 

 they svill be seen in va- 

 rious stages of deve- 

 lopement. At this late 

 period of the formation, 

 bone-cells appear in 

 the ossified intercellu- 

 lar tissue, which from 

 the first formed a con- 

 nection between the 

 systems of tubes, and 

 which iu fully formed 



Section showing the develope- b unltes the Haver- 

 men* of the bone cells and sian systems. W ith this 

 the separation that may\\Q have bone in its 

 be produced between the perfect State. 



c ., From wha.i na 



site and the tissue of the . . ... , 



united cells. stat ed it will be seen 



a, ossified intercolumnar that the cartilage cell or 



tissue; b, ossified parietes corpuscle is the first 



of the united cells; c, the part formed; that this 



Haversian canal in its ru- n generates others . 



dimentary state ; a, bone . ,, , 



cells in their first stage of that the y form the 



developement. linii g of the primary 



tube; that the lining 



becomes the external lamina of an Haversian 

 system : so that the parietes of the cell in 



