12 DR. BKALE, ON THE TISSUES. 



of their surface is also true, but these projections and angles 

 have nothiug to do with the formation of canaliculi. The 

 appearance is exceptional instead of being constant, and a 

 lacuna with numerous canalicv\li may be produced -uathout 

 the existence of an angular cell at all. The mass of germinal 

 matter is oval from the period it first existed as a separate 

 object to the time its nucleus is seen in the lacuna. Into 

 each lacuna forty or fifty or more canaliculi open, and these 

 communicate with those of adjacent lacunae. Surely, if these 

 were formed in the manner described, we ought to be able to 

 demonstrate something like this during the formation of the 

 lacuntfi ; but nothing of the sort has been seen, and the 

 warmest advocates of the theory have only been able to 

 observe a very faint indication of the arrangement Avhicli 

 they believe actually exists. Their drawings only show these 

 processes projecting a very short distance from the cells, and 

 no one pretends to have seen processes from two neighbouring 

 cells in process of communicating Avith each other, as exists 

 constantly in the perfect canaliculi of bone. It is not only 

 very difficult to conceive such channels formed by an out- 

 growth, but it is inconsistent with what is generally observed, 

 to suppose that channels are scooped out in a tissue which 

 has just been formed. The tissue during its formation requires 

 channels for the transmission of nutrient matter just as much 

 as after its formation is complete. 



If the canaliculi Avere formed as described, it seems impos- 

 sible that every observer should have failed to see the pro- 

 longations of the cell undergoing development and coalescing 

 with those of neighbouring cells. The extremities of these 

 tubes which were gradually extending through the matrix 

 Avould be rounded, and would contain germinal matter which 

 Avould absorb the solid matrix, and thus the tube Avould extend 

 through its substance. No such appearance has ever been 

 seen. The canaliculi are no more processes of the cell AA'hich 

 bore their way through the hard material than the tubes 

 Avhicli are foiind in the masses of secondary deposits in the 

 hard Avails of certain vegetalde cells are processes of the ger- 

 minal matter in the centre of the cell. 



Again, it is very difficult to understand why tubes groAving 

 centrifngally from adjacent cells should not grow outAvard, at 

 least at first, in direct lines, and reach each other by the 

 shortest cuts, Avhile, according to my vIcaa-, as the deposition 

 of the calcareous matter commences always at the point 

 Avhere two elementary parts coalesce, Avhere the oldest part 

 of the formed material is situated, it is easy to shoAv how the 

 canaliculi, or spaces left, must be continuous with each other; 



