OF CARTILAGE. 19 



Nuclei, around which no cells have yet commenced to be de- 

 veloped, may be observed in the cytoblastema between the 

 cells in some situations ; for example, a and b. These like- 

 wise contain a nucleolus, and arc somewhat less than the nuclei 

 in the smaller cells. 



The above observations furnish us with a complete repre- 

 sentation of the development of cartilage-cells, and show the 

 accordance of that process with the development of vegetable- 

 cells, inasmuch as they exhibit the simultaneous presence in the 

 cytoblastema both of simple nuclei, and of cells containing a 

 nucleus of similar shape and size upon the inner surface of 

 their walls, and which may be observed in all stages of tran- 

 sition, from such as are scarcely larger than the nucleus they 

 contain, to such as are many times its size. Simple nuclei are 

 first present, developed in the cytoblastema. When these have 

 arrived at a certain size, the cell is formed around and closelv- 

 encompassing them. The cell gradually expands, whilst the 

 nucleus remains lying on a point of the inner surface of its 

 wall. The nucleus, also, increases somewhat in size, but not in 

 proportion to the expansion of the cell. Now these three hy- 

 potheses may be assumed from the above facts ; either the cell 

 is first developed, and the nucleus subsequently, or both arc 

 developed simultaneously, or the nucleus is first developed, 

 and then the cell around it. The first supposition, that the 

 cells are developed earlier than the nuclei, is not possible, since 

 in that case cells would be found at a certain period of deve- 

 lopment without nuclei. The simultaneous development of a 

 cell, together with its nucleus, as two distinguishable struc- 

 tures, is equally impossible, for then we should observe a stage 

 of development, at which as yet the cell and nucleus had not 

 reached the size of the ordinary nucleus. In order to explain 

 the above observations, we must, therefore, have recourse to 

 the third supposition, viz. that the nucleus is first developed 

 and then the cell around it. 



The form of the young cells depends upon the space allotted 

 them for expansion. They are, therefore, cither round or angular, 

 according as the neighbouring cells permit of, or limit their re- 

 gular expansion. Two or more cells are often developed close to- 

 gether in one intercellular space, and thus compress those already 

 formed, and the intercellular substance on the outside of them ; 



