THE MICROSCOPE AND ITS PREPARATIONS. 167 



spikes and pointed scales which lines the whole inside of the 

 tube, all pointing downwards, and especially the strong pike- 

 pointed lances which are thickly set under the hood and on the 

 inner margins of the lid, all pointing backward and downward, 

 you will not wonder that when a fly has once entered those 

 horrid portals he is inevitably lost. There is only one way for 

 him to go, and that is straight downward. I could not imagine 

 a more perfect fly-trap, a more dangerous den for an unwary in- 

 sect to get into. And I have no doubt that many a poor fly at 

 the bottom of that charnel house has recalled his Virgil : 



" Facilis descensus averno est; 

 Sed revocare gradum hoc opum, hie labor est." 



To help you that are not versed in fly-talk, shall I give you 

 Dryden's beautiful translation of that passage ? 



" The gates of hell are open night and day; 

 Smooth the descent, and easy is the way : 

 But to return, and view the cheerful skies 

 In this the task and mighty labor lies." 



In order to make the structure of the inside of the pitcher 

 plant leaf at all apparent and in condition to be seen, I was 

 obliged not only to remove the original coloring matter of the 

 leaf by soaking in chlorinated soda, but also to separate the inner 

 cuticle or skin, which holds all the hairs and spikes and glands, 

 from the rest of the leaf by immersion for a time in a weak 

 solution of potash. Of course the cuticle, thus prepared, has to 

 be again artificially colored in anilines or other colors, in order 

 to make the different parts and structures distinguishable. 



The Utricularia, or Bladder-wort, is another very singular 

 insectivorous plant. It grows on the water, on the surface of 

 shallow ponds, but is not rooted to the ground. It spreads out 

 from five to seven leaves, like the spokes of a wheel, on the sur- 

 face of the water, and these are buoyed up by numerous little 

 air bladders. From the center of these leaves the plant sends 

 upwards its flower stalk, and downwards its root-like branches. 

 These latter bear, among their finely branching fibers, great 

 numbers of little egg-shaped bladders or utricles, not larger than 

 the head of a pin. These bladders have at one end a cunningly 

 arranged mouth, or rather lid, opening inwards, and surrounded 



