314 



EVENINGS AT THE MICROSCOPE. 



cleanses the bundle from tlie fleshy matter which would 

 otherwise obscure the vision, and now I place it on the 

 stage. 



With this power of 400 diameters you see a multi- 

 tude — some twenty or thirty, or more — of very long, 

 slender, straight rods, of a clear yellowish horny sub- 

 stance, set side by side, like a sheaf of spears in an 

 armory. Each one merges, at its upper end, into a 

 sort of blade, which is slightly bent, and which tapers 



PCSniJIG-POLES OF SEEm.A. 



to an exceedingly fine j)oint. But its chief peculiarity 

 is that the blade has a double edge, not like a two- 

 edged sword, the edges set on opposite faces, but on 

 the same face, set side by side, with a groove between 

 them ; and each edge is cut with the most delicate and 

 close-set teeth, the lines of which pass back upon the 

 blade, as in our reaping-hooks. 



These pencils of spear-like bristles are the organs 

 by which the protrusion of the animal is performed. 

 Tlieir action is manifestly that of pushing against the 

 walls of the interior, which on close examination are 

 seen to be lined Avith a delicate membrane, exuded 

 from the animaPs skin. Tlie opposite feet of one seg- 

 ment protrude the pencils of bristles, one on each side, 

 the acute points and teeth of which penetrate and 

 catch in the lining membrane ; the segments behind 



