14 ELEMENTARY STRUCTURE OF ORGANIZED BODIES. 



any tissue, the law is, that they constantly appear where the 

 nutritive fluid penetrates the tissue most immediately ; there- 

 fore it is that the formation of new cells in the unorganized 

 tissues only takes place at the points where they are in con- 

 tact with the organized matter ; in the completely organized 

 tissues, again, where the blood is distributed to the whole of 

 the texture, new cells are produced in the entire thickness of 

 the tissue. 



[ 51. " The process by which the cells evolve themselves 

 into the elementary formations of the individual tissues is 

 very multifarious. The most remarkable differences are the 

 following : 1 . The elongation of the cell into a fibre, which 

 probably takes place in consequence of one or more parts of 

 the cell- wall increasing in a greater degree than the others. 

 2. The division into so many isolated fibres, of a cell elon- 

 gated in different directions. 3. The blending of several 

 simple or primary cells into one secondary cell. 



[ 52. " CARTILAGE. The cartilages are distinguished 

 among all the tissues of the human body, by containing the 



largest quantity of cytoblastema, which is 

 also extremely consistent (fig. 3). The 

 quantity of cytoblastema, however, differs 

 greatly in different cartilages. It is, for 

 instance, much smaller than usual in the 

 branchial cartilages of the larva of the frog 

 (fig. 4). Here the cells may be observed 

 flattening one another as soon as they 

 touch. The first formation, and subse- 

 Fig. 3. Cartilage; the q uen t growth of cartilage, take place in 

 nidus of the os ileum, J n ? } . p^tohlaatema is first nrn 

 but as yet without Sucn W S > ma C y l na 1S nrst P ro " 



earthy deposit, from the duced, m which cells then form, whilst, at 



foetus of the sow. the same time, fresh cytoblastema arises, 



within which, again, cells are evolved as 

 before, and so the process goes on. As the cartilage is without 

 vessels at first, the formation of new cells only proceeds on the 

 superficies of the substance, or, at all events, in its vicinity ; 

 in the situation, therefore, where the cartilage is in immediate 

 contact with the nutritive matter. The production and growth 

 of the cells of cartilage are exhibited in figure. 4 . In the cyto- 

 blastema, on the surface of the cartilage at a, or between the 

 new-formed cells at b, new cell- nuclei are arising. Around 



