TISSUES OF THE BODY. 



171 



Fijr. 161. Diagram of well-deve- 

 loped old hyaline cartilage, with 

 various kinds of cells. 



stance, surround isolated cells or groups of the same, at one time very 

 distinct, at another blending in their periphe- 

 ral portions into the matrix (fig. 161). These 

 are the long-known cartilage-capsule's, which 

 we have already considered in a former part 

 of our work (p. 87). 



We are here met by the important ques- 

 tions: how have these capsules originated? 

 what is their relation to the cell and inter- 

 cellular substance ] and what is the source of 

 the latter] 



The opinions of histologists on the points 

 in question have varied from the earliest days 

 of microscopy in the most marked way. It 

 was long ago supposed, under the belief in the 

 spontaneous generation of cells and the doctrine of blastema, that the 

 intermediate substance was gradually insinuated between the cells ( 102), 

 and that the cartilage-capsule was formed of a modified layer of the latter 

 around the cell : consequently, that the capsule was deposited externally 

 upon the cell-body. On the other hand, some, while they allowed the 

 origin of the apparently homogeneous intercellular substance to be that 

 just stated, still looked upon the cartilage capsule as a product of secre- 

 tion from the cell, fusing at its periphery with the matrix. According to 

 a third view (1), the capsule, as well as the intercellular substance, is a 

 material supplied by the cartilage cells. But it is still a subject of con- 

 troversy whether the capsule and groundmass are to be looked upon as a 

 secretion of the cells, which has become solid, or a part of the body of the 

 la'tter, which has undergone metamorphosis; or, again, whether, as a rule, 

 this intercellular matter is to be considered structureless or the reverse. 

 The last of these three views is, in our opinion, the only one tenable at 

 the present day (2). 



We are able, indeed, by means of certain reagents, to demonstrate with 

 complete certainty that the so-called intercellular substance of many car- 

 tilages is only apparently structureless (fig. 162). 

 This is seen to be the case in the frog, while it is 

 less distinctly evident and more difficult of demon- 

 stration among mammals. It is, in fact, by a 

 process of repeated formation of capsules that the 

 matrix is produced and increased in quantity. The 

 whole ground-work of cartilage consists of nothing 

 but a number of large systems of capsules, which 

 have become fused into one another. Each car- 

 tilage cell, therefore, takes a part in this process. 

 In many cases these concentric laminae in the cap- 

 sule appear in section of exactly the same refrac- 

 tive power, and consequently it was formerly sup- 

 posed that the intercellular substance of cartilage 

 was homogeneous and structureless. But if, on the other hand, the 

 youngest layers in the system presents different optical bearings (which 

 occurs, as we know, not unfrequently), the term cartilage - capsule is 

 usually applied to them. 



But although so much is, in our opinion, certain, yet the problem as 

 to whether these capsules are the products of secretion of the cell-body 



Fip. 162. Thyroid cartilage 

 from the pig, after treat- 

 ment win chlorate of pot- 

 ash and nitric acid, showing 

 the intermediate substance 

 resolved into the portions 

 belonging to each cell. 



