( 67 ) 



* x\fter this, I examined the matter or fubftance \vith wliich thel'e 

 fcales are coveretl, whicli, as well as the I'cales, has been generally 

 deemed nothing more than flime, and is by mod perfons thought 

 to be an excrenientitious matter, adhering to this fpecies of Filh ; 

 but I am now convinced by experience, and the cleareft ocular 

 demonftration, that this fuppofed flime does not collect on the 

 animal's body from without, but is really part of the body itfelf ; 

 forafmuch as this fubftance, althougli it appears to tlie naked 

 eye, and very often through the micro fcope no otherwife than like 

 a cryllaliine or pellucid humour or fubftance, yet in faft it is no 

 other than a congeries or colIe(51:ion of veins or vedijls, which in their 

 exquifite fineneis or flendernefs do almoft exceed belief, fpreading 

 themfelves one among another in fuch an incomprehenfible and 

 immenfe number of branches, that I could not contemplate them 

 without the greateft admiration. Indeed, many were lb thin and 

 flender, that I could not difcover them without the moll carefid 

 attention, and I thought it probable that there might be others flill 

 more minute, fo as entirely to cfcape the fight. Such of thefe 

 velTels as I could diftin6lly perceive, I judged to be fo fmall 

 (meafurJng them by my eye) that if one of the globules-f- of blood 

 from whence its rednefs proceeds, were to be divided into a thou- 

 iand parts, not one of thofe parts could pals through thefe wonder- 

 fully thin and flender vefiels. 



From thefe obfervations I concluded, that this fubftance only 

 anfwers the purpofe of a membrane or fkin lying next to the fcales, 

 and that, when an Eel is creeping through a narrow pafl'age or hole, 



* Thefe obfervations of the Author on the Eel appear to have been written poflerior to 

 the time when he publifhed the preceding ones, and it fliould feem, that what he before 

 defer ibcs to be an appearance like a cobweb adhering to the fcales, is the efFedt of the vefiels 

 here defcribed. 



-j- The author's computation of th? fize of a g! ibule of blood, will be found in another place, 

 where he treats of that fubjedt. 



I 3 



