392 EVENINGS AT THE MICROSCOPE. 



are seen running down the body of this pretty leaf, which 

 do not appear to mark irregularities of the surface, and 

 therefore are probahly internal. Ehrenberg calls these 

 and similar collections of granules " ova," or eggs ; but 

 this is to cut the knot instead of untying it. There is no 

 sufficient reason to believe that these animals increase by 

 ova. 



About the front of all these Euglena, you may discern 

 now and then a slight flickering or quivering in the water. 

 The power we are using, though best for the general 

 display of the form, is insufficient to resolve this appear- 

 ance : I will put on a higher objective. You now see that 

 there proceeds from the frontal part of the body a long 

 and very slender filament, which is whisked about in the 

 manner of a whip -lash. This is considered to be the 

 organ of locomotion ; but I rather doubt that such is 

 the function ; the smooth and even gliding, often rotating, 

 action of the creature, seems more like that produced by 

 minute and generally-distributed cilia, than that caused 

 by the lashings of a single long thread. 



Yet two more species of this extensive genus we dis- 

 cern in this well-stocked drop of water. They have 

 received the appellations of the Pear (E. pyrum) and the 

 Sloth (E. deses). The former is the most minute we have 

 yet seen and seems to be scarce ; but it is highly curious 

 and interesting in appearance. It much resembles in 

 outline a fish of the genus Balistes; the muzzle being 

 somewhat protruded and truncate, and the form rhom- 

 boidal ; it terminates in a slender pointed tail. The body 

 is obliquely fluted, which gives a very singular effect ; for 

 from the transparency of the tissues the lines of the 

 opposite side can be discerned crossing those next the 

 eye, and dividing the animal into lozenge -shaped areas. 

 The colour is sparkling green, but the tail and the edges 

 of the body are clear and colourless, and there is a bright 

 red eye. At other times this Euglena takes the form of a 



