VIEWS OP THE MICROSCOPIC WORLD. 



Fig. 10. 



This species possesses an oval form, is furnished with two cilia, and increases 

 by self-division, which takes place both across and lengthwise of the body. 



THE GREEN-EYE MONAD. In figure 10 is delineated a species of the monads 

 in which Ehrenberg supposed that he had discovered a visual organ. 

 It is of an egg-shaped form, and moves in the direction of its length 

 Iby the aid of a cilium (a 6), which is nearly as long as the cell. Its 

 color is a rich green, and the eye-speck, which is red, is distinctly 

 seen, as shown in c. This organism is found amid water-plants, and 

 varies from one seven-hundred-and-twentieth to one twenty-three- 

 hundredth of an inch in length. In the figure it is magnified eight 

 hundred times in length and breadth. 



THE BREAST-PLATE MONADS. Many of the monads are found clustered in one 

 Fig.n. community, and move together as one body. This mode of 

 existence occurs in the breast-plate monads, which have received 

 this name from the form in which they are arranged. A group of 

 these singular plantules is shown in figure 11, and a single one in 

 figure 12. The breast-plate monads are found in clear water, both 

 salt and fresh, and consist of sixteen globular bodies of a pure 

 green color, enclosed within a flat, transparent case of a pearly 

 hue. In this they are regularly disposed in a square or oblong form, 

 the four central individuals being usually larger than the rest. Their mode of in- 

 crease is by self-division, and when this occurs, the group divides across the 

 Fig. 12. middle in two directions, separating into four clusters, each containing four 

 ^L monads. No socner has a group thus separated, than each of the plantules 

 which composed it increases in size, and soon subdivides into four monads, 

 and the original number of sixteen is seen in every one of the four clusters. Ere- 

 long, these again separate into four portions, and the species thus multiply intermi- 

 nably. The tablet, though containing sometimes less than sixteen individuals, 

 never exceeds that number. Its form is often irregular; which is caused by the 

 separation of some of the monads from the cluster when they have attained their 

 full growth. Each of the individuals composing the group is connected with the 

 rest by means of six threads or tubes ; these, with the two cilia, a and 6, are seen 

 Fig. 13. in figure 13, where a monad is exhibited attached to a portion of the 

 transparent case. The length of the tablet is not greater than one two- 

 hundred-and-eightieth of an inch, and that of each monad ranges from 

 about one Jive-hundredth to one-thousandth of an inch. A single structure, 

 when free from the case, as delineated in figure 12, swims by the aid 

 of its cilia in the direction of the length of the cell, with its ciliated 

 end foremost, as other monads ; but the group perform various evolu- 

 tions, sometimes proceeding horizontally, sometimes upwards, and 



again rolling on the edge like a wheel. The extraordinary activity of 



these wonderful little atoms is distinctly beheld when a small portion of coloring 

 matter, as indigo, is introduced into the water in which they are discovered ; the 

 whirls and currents will be seen in the fluid, caused by the vibration of the two 

 cilia belonging to each plantule. 



When & group is in progress, thirty-two of these organs are consequently in 



