144 THE MICROSCOPE. 



wise they are poisoned by it. This important discovery of feeding the 

 little things on colour set aside the opinion of previous naturalists, 

 that they effected nutrition by cuticular absorption ; it also led to a 

 classification, not, as formerly, by shape, but structure. 



Monas Termo, or End Monad. The name given these animalcules 

 is from their appearing, under the greatest power of the microscope, as 

 mere ends or points ; in fact, to catch a glimpse of them is very diffi- 

 cult, as they are round in shape, and of a bright transparent appear- 

 ance. 



Monas Atomus. The atom monad has always a round body, and 

 varies from the 6000th to the 3000th of an inch in diameter ; it is of 

 the colour of water. 



Monas Grandis. The great monad appears in a variety of bright 

 colours ; it is oval in form, and when floating on the tops of ponds and 

 ditches, the water seems encrusted with slime. 



Monas Mica. The grain monad is about the 1500th of an inch in 

 size, and two oval-shaped bodies are perceptible in it ; but that which 

 renders it an object of interest when viewed through the microscope, 

 is a beautiful halo that surrounds it, which is supposed to proceed from 

 cilia, or hair in motion; it is often seen to revolve on its own axis. 



Monas Uva. The grape monad is so named from a resemblance to 

 a bunch of grapes, when the animals form themselves into clusters, as 

 they usually do. They are oval in form, have two cilia, and are won- 

 drously active in pursuing and devouring their lesser brethren, several 

 of whom they consume at a meal, having, according to Ehrenberg, no 

 less than twelve stomachs to fill. They multiply both by eggs and 

 self-division ; scientifically, they are termed oviparous and gemmipa- 

 rous, When they propagate in the latter mode, their bodies divide 

 into four parts, forming as many distinct animals. 



The Gonium, or Tablet Monad. Enclosed in a flat hyaline envelope, 

 irregular in shape, and not larger than one three-hundredth of an inch 

 in length, is discovered a happy community of sixteen bright green- 

 coloured cell masses, which at times exhibit a rhythmical contraction 

 and expansion, as in the Volvox. These are sometimes called Breast- 

 plate Animalcules (fig. 95, No. 3). They move about in all directions, 

 upwards and downwards, forwards and backwards, and rolling on the 

 edge like a wheel. The twenty-four cilia projecting from the sides, 

 and eight from the centre, appear to be actively engaged in satis- 

 fying that first law of nature, self-preservation by food. They are 

 bound to each other, not only by mutual will,, but by six threads or 

 tubes. The four centre animals are usually bigger than the others. 



