The Glow- Worm and Other Beetles 



Though perfectly visible without the help 

 of a lens, these puzzling spots call for the 

 microscope if we wish to study them in de- 

 tail. We then find that the adipose tissue is 

 made up of two kinds of vesicles: some, 

 bright yellow and transparent, are filled with 

 oily drops; the rest, opaque and starch-white, 

 are distended with a very fine powder, which 

 spreads in a cloudy trail when the vesicle 

 containing it is broken on the object-slide. 

 Intermingled without apparent order, the 

 two kinds of bags are of the same shape and 

 the same size. The first go to make up the 

 nutritive reserves, the fatty tissue properly 

 so-called; the second form the white dots 

 which we will study for a moment. 



An inspection under the microscope tells 

 us that the contents of the white cells are 

 composed of very fine, opaque grains, in- 

 soluble in water and of greater density. 

 The use of chemical reagents on the object- 

 slide proves that nitric acid dissolves these 

 grains, with effervescence and without leaving 

 the least residue, even when they are still en- 

 closed in their vesicles. On the other hand, 

 the true fatty cells suffer in no way when at- 

 tacked by this acid; they merely turn a little 

 yellower. 



Let us take advantage of this property to 

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