18 DR. BEALE, OX THE TISSUES. 



large stellate elementary parts were very readily separated 

 from each other. The leeturer hoped it would be particu- 

 larly remarked that in this specimen the central part of each 

 is very darkly coloured by carmine ; external to this the 

 structure is colourcdj but the colour becomes fainter in the 

 most external portions^, and the outermost part of each fibre 

 and its prolongations_, are perfectly colourless. The fibrous 

 character of the tissue is sufficiently manifest. As in many 

 other cases^ the germinal matter is here seen in the centre 

 of the mass^ and is gradually giving rise to the production 

 of formed material^ the oldest and that which is perfectly 

 formed being at the greatest distance from the central mass, 

 while that which was but recently germinal matter, and is 

 now in a transition state, is continuous with it. The 

 latter is slightly coloured ^nth. carmine, while the perfectly 

 developed formed material is not coloured at all. 



In concluding his sixth lectiQ'e Dr. Beale remarked that 

 the early formation of bone was not the least like the early 

 formation of a tissue with stellate cells. In the former the 

 so-called cells (masses of germinal matter with formed ma- 

 terial externally) are round or oval at every period of their 

 development, and may be separated from each other without 

 difficulty. In the stellate tissue the masses of germinal 

 matter are connected together for a considerable period of 

 their existence ; at first the points of communication are 

 wide, but they gradually become narrower and narrower as 

 the distances increase, and at last they are reduced to nar- 

 row processes which at length undergo conversion into formed 

 material. The germinal matter of the different masses may 

 communicate through these processes up to a certain period, 

 but gradually they become more solid, and then the masses 

 are distinct, but still connected to each other by narrow 

 cord-like processes. 



The nutrient material passes to the germinal matter of 

 each mass, and to that prolonged to each through the formed 

 material which is deposited in the intervals. In some stellate 

 tissues fluid only exists in this situation, which is afterwards 

 absorbed, leaving spaces between the walls of the tubes into 

 which air passes. 



The dentinal tubes, and the tubes of the stellate tissues, 

 therefore, do not correspond to the canaliculi of bone. Their 

 counterpart is seen in many vegetable tissues, at the point 

 where the separate masses of germinal matter are connected 

 together; while the chaimels corresponding to the canaliculi 

 are the poi'cs which extend through the secondary deposits 

 in vegetable cells. 



