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Researches on the Structure of the Scales of Fishes. By Dr 

 L. Mandl* 



Chap. I. — Historical. 



The researches made by authors respecting the scales of 

 fishes have in general been confined to the examination of a 

 very small number of them ; they were merely observed 

 through a magnifying glass, and their forms imperfectly describ- 

 ed, no one entering upon the subject of their internal structure. 

 M. Agassiz, when directing attention to them as affording 

 important aids for the classification of fishes, is, in like manner, 

 contented with merely determining their forms. 



It is long since Borellus (Petnis, observationum micro- 

 scopicarimi centuria. Hag. Com. 1656) observed that these 

 scales presented concentric lines divided" by rays and black 

 points. " Squamai piscium apparent si aspiciantur, lineis 

 orbicularibus multis distinctee, et in parte qua cuti adhaerent, 

 radiis ac pvinctis multis transcurrentibus divisae." The figure 

 he gives of a scale entirely corresponds to this imperfect ob- 

 servation, the date of which may be said to be in the very 

 dawn of micrography. 



Hooke (in his Microyraphia, London, 1667, p. 162) gives a 

 figure of the scales of the sole, more accurate than those of 

 any author that has succeeded him. Guided by ovu* own re- 

 searches, we can easily recognise in his figure the form of 

 the teeth and longitudinal canals. His description of these 

 details is very brief ; he thus expresses himself in regard to 

 the teeth : — " Through an ordinary single magnifying glass, 

 they looked not unlike the tiles on a house," and he adds that 

 they are " transparent and hard- pointed spikes." The longi- 

 tudinal canals are " small quills or pipes, by which, perhaps, 

 the whole may be nourished." 



The observations of Leuwenhoek are among the most in- 

 complete which that author has made ; yet they were accepted 

 by all his successors. He says (Cont. arc. nat. Lugd. Batav. 

 1722, (Op. omnia, p. 3) Ep. 107, p 191, 1696 ; Ep. phys. 

 Delpliis, 1719 ; Ep. 24, p. 213, 1716) that a new scale is 



* From Ann. des Sciences Nivturelles, Juin, 1839. 

 vor,. xxviir. no. lv, — JANrAnv 1840. h 



