122 Dr L. Mandl on the Scales of Fishes. 



shared in the ideas of Leuwenhoek ; and that it was impossi- 

 ble for them to comprehend truly either the form or organiza- 

 tion of scales, from not having employed the most powerful 

 means of investigation, that is to say the microscope, which 

 has procured more complete results for us.* 



Chap. Ill Scales considered as affording Characters for Classifi- 

 cation. 



The most important question in the study of natural his- 

 tory, is the determination of natural characters, that is to say, 

 of characters which bring together the inherent properties of 

 animals, — which are proper to them in their natural state, — 

 and which can be studied either by observing an entire body, 

 or only a few detached parts, and that always without the as- 

 sistance of other sciences. Now, Avhat is most important in 

 these researches, is precisely to determine characters in inti- 

 mate relation with the nature of the animal, its organization, 

 the anatomy and physiology of its body, which are, in short, 

 essential, and undergoing no change with the accidents of ha- 

 bitation, food, &c. 



It is the just determination and appreciation of these cha- 

 racters which can furnish us with true and precise notions of 

 species, genera, and families, and enable us to avoid the errors 

 committed by those who imagine they have found, in the most 

 insignificant details, sufficient characters to constitute a new 

 species. Have we not thus seen botanists make two different 

 species of the same flower, as it happened to grow on the sides 

 or in the bottom of a ditch, and might, from this cause, more 

 or less differ in the brilliancy of its flowers ? Do we not daily 

 see ichthyologists and zoologists creating new species accord- 

 ing to changes of colour, size, fee, — changes which are alto- 

 o-ether accidental, and depend entirely on the influences of 

 climate, food, &c. But, apart from the small value attaching 



* The second chapter of Dr Mandl's paper is devoted to the explanation of 

 the structure of scales. This we have been obliged, in the mean whUe, to 

 omit, as it requires a gi-eater number of illustrative figures to render it fully 

 understood, than we can at present find room for. The omission, however, 

 is less to be regi-etted, as it in no way affects the interest or value of the two 

 other chapters, eacli of which is complete in itseli— Editok. 



