35G SPECIAL HISTOLOGY. 



over, even in perfectly normal bone, in the adult, I have met 

 with places (some of which, independently of me, have also 

 been lately described by H. Meyer (1. c.) ), such as the 

 symphysis pubis, the synchondroses of the vertebra, and those 

 of the ilium, sacrum, and the points of insertion into the bones 

 of certain tendons containing cartilage-cells. In all of these 

 situations, at the line of junction between the cartilage or 

 tendon and the bone, cartilage-cells of the most characteristic 

 aspect may be seen, lying free in the cartilaginous matrix, and 

 presenting the most various degrees of transformation into 

 bone-cells ; some, in particular, having thickened walls, aud a 

 more or less copious deposit of calcareous particles ; while others 

 are almost perfectly-formed bone-cells, with pores and a more 

 homogeneous wall (fig. 123); so that I am able to afford a 

 certain support to the statement given above with respect to 

 the mode of origin of the bone-cells, by the conditions pre- 

 sented in normal tissues also. In the last-named situations I 

 have, likewise, very distinctly and very frequently noticed, 

 half or wholly ossified parent-cells, containing from 2 to 12 

 secondary cells. 



There is another point in the development of the bone-cells 

 still obscure, or at least that has not been directly observed, 

 viz.: how their pores or canaliculi become branched cavities, 

 communicate with those of other cells, and acquire open 

 orifices in certain situations. All that is apparent in rachitic 

 bone and elsewhere, is merely the circumstance, that the 

 thickening of the ossifying cartilage-cells does not proceed with 

 a straight but with an indented border, which is the case 

 in fact from the beginning up to their completion, and that 

 the bone-cells have, at first, more simple prolongations than 

 afterwards. Observation teaches nothing beyond this. Now, 

 as there can be no doubt that the canaliculi anastomose very 

 freely, and also, that they frequently open on the outer surface 

 of the bone, or into the cavities in its interior, I do not for 

 a moment hesitate to express the opinion, that the canaliculi, 

 arising as simple branches from the lacuna, are continued or 

 further developed by absorption of the already formed bone- 

 substance. How such an absorption takes place, cannot, it 

 must be confessed, be explained; but that affords no ground of 

 objection to the opinion, because we see a similar process, 



