140 FIELD AND FOREST. 



forward, and the final or tail end finishing its action before the second 

 step is taken. The transverse muscles (and this is probably their most 

 important, if not only, function,) draw the setae into the abdominal 

 cavity when the creature is preparing to take another step, and when 

 it becomes necessary to present a smooth, unresisting surface to the 

 earth, as often happens when, at the jar of an approaching footstep, it 

 quickly retreats into its burrow. 



In a prosy talk about muscular action, there is very little that is 

 graceful and attractive, however much we may have in mind the many 

 graceful and attractive movements those muscles ma) cause in the 

 bodies possessing them. In curved lines, on the contrary, there is al- 

 ways a grace, in the mysterious always a charm. Within this worm we 

 find the curves, and in these curves the mystery. 



When the body is opened from the dorsal surface, the unaided eye 

 at once perceives in each abdominal chamber, on both sides of the 

 alimentary canal, a series of minute whitish spots with still more minute 

 prolongations extending toward the median line. The pocket lens 

 says the spots are knots, and the probing needles announce that they 

 are floating free in the cavity, attached to the septum by the long 

 thread. Neither is quite right. You have heard the story in which 

 the crab was said to be red and to walk backward — correct in all but 

 two particulars. So in this case, there are no knots and the attach- 

 ments are short. Under the microscope these white bodies are seen 

 to be long tubes, so curved and convuolted that they seem like a new 

 kind of puzzle. They are a puzzle. 



If any one should vivisect a worm — of course no one would, but if 

 he should — he would see that these vessels are lined with ciliated 

 epithelium lashing actively, and apparently doing nothing else; and 

 as the victim gradually expired, the motion would grow less, until 

 finally only at long intervals a slow undulation would sweep through the 

 tubes, and like a miniature tidal wave, sink to stillness on the shore of 

 a sudden curve. 



The convoluted portions are in one chamber, while the free extremi- 

 ty, containing the internal orifice, is in that one immediately in front. 

 The latter, generally open toward the middle line, enters a tube which 

 is flat until it passes the septum, and is somewhat reniform in shape, 

 with a thickened margin surrounded by long cilia. The free ex- 



