2:80 Dr L. Mandl's liesearches on the 



nearly of the form represented at fig. 3 of the plate. We perceive longi- 

 tudinal canals emanating from the focus, and between these concentric 

 series of lines which we shall observe more in detail. This scale, which 

 is magnified three hundred times, shews that the concentric lines are com- 

 posed of insulated cells, each of which presents the cell i^roperlyso call- 

 ed, and its base. It is separated from the neighbouring cells bj- a nar- 

 row furrow, so that each cell with its base rests insulated on the base of 

 the next cell. Longitudinal canals are likewise observable : sometimes 

 the posterior edge of the base is distinct ; each cell presents on one 

 side the thickness of its wall indicated by a double line. 



In Gadus euxinus, the cells are still insulated, but the bases are already 

 united, and extend in parallel plates to the longitudinal canals ; we per- 

 ceive distinctly the two layers of which the scales are composed ; the 

 lower one forms the bottom of the canals, the upper one the base of the 

 cells. 



The Eel presents one degree of further development ; the cells form 

 lines which become more distinct around the focus; manj' series only are 

 separated by a wide space ; the bases of the insulated cells are all united 

 in a uniform layer ; the cells are surrounded by a double line. 



The cells on the surface of the scales of Motella tricirrata (pi. III. 'fig 10), 

 are a kind of bubbles disposed in series, and prominent, so that they can 

 be made to lie over on either side we may wish. The upper layer is di- 

 vided only by the longitudinal canals. 



We have represented (pi. III. fig. 11) a portion of the scale oi Mullus 

 barhatits, taken from the lobe between two longitudinal canals ; we sec 

 at the same time, the composite series of the insulated cells, and others, 

 which permit the view of the cells which compose them ; these latter be- 

 gin to be confounded, only the exterior edges remaining, which at last 

 disappear. 



Serranns scriba (pi. III. fig. 12) affords a verj' remarkable example of 

 the origin of these lines by the fusion of the cells. We see very distinctly 

 an edge of the base occupied bj' globular cells, very minute, at first well 

 marked, but gradually diminishing, till at last they form only a crenulated 

 line. 



The carp has scarcely any cells in its lines, and the greater part of the 

 latter appear in a form which we shall examine afterwards. 



In the series of scales which we have successively noticed, we have 

 had examples of cells sometimes elevated on one side only, indicating 

 their thickness by a double line ,* sometimes elevated throughout their 

 whole circumference, and which can be made to fall either on one side 

 or another, but always placed on a separate base, which is verj- distinct 

 from the inferior layer of the seale^ and which, in common with the cells 

 and corpuscles disposed in it, form the superior lajer. 



We have likewise followed, in this series of scales, their successive 

 fusion, that is to say, their union with each other in order to form the 

 lines which we have named cellular lines, and which, without this preli- 



