68 CONNECTIVE TISSUES CARTILAGE. 







the later stages, the nuclei of the corpuscles, though still discoverable on 

 careful examination, are to a great extent obscured by the oily contents of 

 the cells ; and Toldt 1 and Flemming 2 from experiments with picro-carmine 

 as a coloring agent, believe they can demonstrate the persistence of a thin 

 layer of protoplasm immediately beneath the cell-wall, in perfectly mature 

 fat-cells, and this they regard as possessing the power of secreting the oil 

 contained in the cell. When an animal is starved, the oily material is con- 

 tinuously withdrawn from the cells, and its place is supplied by a serous 

 fluid, the cells still preserving their round form. If now abundant food be 

 given, a series of changes similar to those above described may be observed, 

 the cells becoming filled at first with minute oil-globules, which afterwards 

 coalesce to form one of large size. If inflammation is established in adipose 

 tissue by the injection of solution of iodine,,or other irritant, the endogenous 

 formation of cells can be very distinctly seen (Fig. 28). 



47. CARTILAGE. Cartilage presents two forms: the temporary and the 

 permanent; the former exists in considerable quantity in the foetus, occupy- 

 ing the position and constituting the foundation of the principal bones of 

 the skeleton, certain portions of the vault of the cranium alone being ex- 

 cepted. In all instances, the microscopical structure is essentially similar, 

 the tissue presenting cells separated from one another by a greater or less 

 amount of intercellular substance or matrix. In some situations, as in the 

 chorda dorsalis, the cells appear to be in direct apposition with one another, 

 their cell-walls, slightly thickened, alone representing the matrix; in other 

 cases, as in ordinary articular cartilage, the cells appear to be scattered 

 through the intercellular substance, which forms a large proportion of the 

 whole mass. W. Miiller 3 describes the central cells of the chorda dorsalis as 

 presenting fine punctations, which are probably the expression of porous 

 canals. Heitzmauu 4 describes processes given off from the cells which trav- 

 erse the matrix in all directions. The matrix in the permanent cartilages 

 of the joints and ribs, appears as a homogeneous and structureless material; 

 but in the cartilages connected with the organs of sense as in the cartilages 

 of the nose, eyelids, and ear, and in the epiglottis it is of a yellowish color, 

 and is pervaded by elastic fibres, and from this form of tissue the transition 

 is easy to the fibro-cartilages, exemplified in the symphysis pubis, the inter- 

 vertebral substance, the interarticular cartilages of the knee and other joints, 

 the glenoid and cotyloid ligaments, and the cartilages lining the grooves for 

 tendons, in all of which the matrix is almost entirely converted into firm 

 and close-set interlacing connective-tissue fibres. Dr. Beale has shown that, 

 if a thin section of cartilage be carefully examined whilst in course of de- 

 velopment, it is impossible to discover any distinct line of demarcation be- 

 tween the substance of the matrix and the contents of the cavities or cells 

 which are distributed through it. The gradation between the two may, 

 however, be made obvious by soaking the section in carmine, which scarcely 

 tinges the peripheral portion, whilst it deeply dyes the central, staining the 

 intervening zones less and less strongly in proportion to their distance from 

 it (Fig. 30). Thus it appears that the true view of the nature of cartilage 

 is to regard it as made up of an aggregation of spheroidal segments of pro- 

 toplasmic substance or "germinal matter," each of which has the power of 

 being converted, at its surface, into that kind of formed material which is 

 termed "chondrin," so that these particles become separated from each 



1 Wiener Sitznn^s-hcrichto, Band Ixii, p. 465. 



- Sehiiltzc's Arcfaiv, H.-md vii, p. 328. 



3 Jormisclie Zeitsdi., B;md vi, p. 3'27. 



4 Wien. Mod. Zeit^cli., 1873, p. 38. 



