Scales of Insects and Fish. 45 



They are not quite so, however, in reality, and a 

 sketch of them, when magnified eighty diameters, will 

 best explain their appearance (fig. 5). 



The scales of the sole, and of many other fish, are 

 covered with similar lines. A sole's scale is repre- 

 sented in fig. 6. The lines on it are coarser than those 

 in the perch's scale, except just in the centre near the 

 ray-like spikes, where there are some finer lines 

 curiously arranged. These spikes are the part of 

 the scale which are outside, and give its roughness to 

 a sole's skin. The other end is the root of the scale, 

 and is rather deeply sunk in the skin. 



The eel's scales are concealed altogether. When 

 I first began to prepare objects for the microscope, I 

 read in some old book that these were worth looking 

 at; so I procured a dry piece of eel- skin, but it was 

 long before I could find what I was in search of. I 

 scraped and scraped with a knife, and examined the 

 scrapings with a microscope, magnifying them 20 times 

 40 times perhaps 100 but no scales appeared. 

 I forget how I contrived to make them out at last. 

 But if I take a little piece of eel-skin and view it as 

 a transparent object, magnified rather more than four 

 diameters, the first thing I see is that the skin is 

 covered with star-like spots, and next I observe the 

 scales lying close together (fig. 7). And this is the 

 way to get at them : I take the little scrap of skin 

 and tear it in two, exactly as if I were splitting a 

 card, for the skin consists of two layers. I can then 

 quite plainly see the scales sticking to the under 

 surface of the spotted piece, that is, lying between 



