CUTTLE-BONE. 167 



seen in the common Cuttle-bone, as it is called, this being the 

 internal skeleton, if it may be so termed, of the common Sepia 

 (Sepia officinalis), which is so often found on our coasts, especially 

 after a gale. This year (1875) I found eight of these Cuttle- 

 bones on the Margate sands, and all within a space of some 

 twelve feet square. 



This so-called bone is really composed of the purest chalk, for 

 which reason it is in great request as a dentifrice, being easily 

 scraped to almost impalpable powder when wanted, and not liable 

 to be spilled, as is the case with any ordinary tooth-powder. 



It is exceedingly light so light, indeed, that it floats like a 

 cork, even in fresh water. Now, as chalk is very much heavier 

 than water, we may naturally ask ourselves how this lightness 

 is obtained. If the upper surface be examined, it will be seen 

 to be traversed by a vast number of wavy lines, something like 

 the markings of " watered " silk. These show the lines of 

 demarcation between the multitudinous rows of pillars of 

 which the whole structure is formed. 



If the " bone " be sharply snapped in the middle, and the 

 particles of white dust blown away, a wonderful structure 

 presents itself, which can be partially discerned by the naked 

 eye, though a microscope is required to bring out its full 

 beauties. 



Even with an ordinary pocket lens we can make out some 

 of its wonders. The object looks like a vast collection of 

 basaltic columns, except that the pillars are white instead 

 of black, and they are arranged in rows with the most perfect 

 accuracy, just as if the place of each had been laid down 

 with rule and compass. They are scarcely thicker than 

 ordinary hairs, but they are beautifully perfect, and rise in 

 tier after tier as if they were parts of a many-storied building. 

 As a definite space exists between the pillars, the reader will 

 understand why the whole structure should be so much lighter 

 than water. In order, however, to see these wonderful pillars 

 in perfection, a very thin section should be taken, and viewed 

 with polarised light. 



ANOTHER excellent example of Pillars and Flooring is to be 

 found in the nests of various Wasps, including that of the 

 Hornet. 



