282 Dr L. Mandl's Researches cm the 



some time, the corpuscles almost entirely disappear, and salts are depo- 

 site. 



These corpuscles are placed in the tissue near the cellular lines, in the 

 bases of the latter, and in a particular tissue laying above the lower bed of 

 the scale. This tissue has no particular organization ; it is an amorphous 

 tissue, like that in which the corpuscles of bone arc deposited. 



This tissue, which contains the corpuscles along with the cellular lines 

 and their base, we shall call the upper layer of the scale. The organiza- 

 tion which we have explained appears to us to bring it near to corpuscu- 

 lar cartilages, which are not ossified. 



The fibrous layer. — If we rub off the upper surface of a scale with a 

 knife, in so doing we remove the cellular lines, their bases, and the cor- 

 puscles, and we then have a view of the under layer, composed of fibrous 

 lamellse, the fibres crossing each other at regular angles, but all following 

 the same direction in the same lamella. (PI. III. fig. 14.) 



If we tear the scale instead of scraping it, we then tear the under layer 

 along with the rest, and thus divide the lamellse into a great number of 

 fibrous bundles, or even single fibres. This organization is altogether si- 

 milar to that of fibrous cartilages. 



When tearing a scale in this manner, it sometimes happens that we 

 meet with fragments in which tlie cellular lines with their bases are seen 

 to pass beyond the edge, an evident proof of the difilrence of these sepa- 

 rate layers. 



There arc many scales in which we can perceive the inferior layer with- 

 out the necessity of tearing it ; such are the scales of the Carp. We then 

 sec at the side of the bases of the cellular lines very closely placed strise, 

 which are just the fibres of the under layer, and which are disposed in 

 different directions. 



This layer is thickest at the focus of the scale and thinnest at the edges. 

 We shall afterwards see how the formation of the scales causes these dif- 

 ferences in thickness. 



It has been already stated, in treating of the longitudinal canals, that the 

 latter arc sometimes simple furrows formed hy the interruption cf the upper 

 layer of the scale, and by the pressure alone of the under layer. ' If we ex- 

 amine the edge of scales (pi. III. fig. 4) we see distinctly how it is that tlie 

 bottom of these canals is continuous with a broad space which we call 

 Uie marginal space, and which is formed solely by the under layer of the 

 scale. This space appears on the basal margin as well as on the lateral 

 ones. If the fibres do not appear at first sight in these marginal spaces, 

 they can always be rendered visible by tearing the scale. 



These marginal spaces are represented not only in die scales indicated, 

 where their formation by the inferior layer is most evident, but they arc 

 likewise seen in a great number of other scales. 



The Focus. This is the name which we have applied to the point to- 

 wards which all the longitudinal lines are directed, but which is not 

 always situate in the centre of the scale. It is occupied by very large 

 corpuscle!?, pale and thin, and by interrupted cellular liaes^ broken, as it 



