MICROSCOPE IN FRESH WATER. 43 



Some of the spores formed by the confervse move 

 about by the agency of little organs called cilia. 

 These are mere extensions of the motile matter of 

 the cell, and are found very commonly in the 

 animal kingdom. Occasionally, a number of these 

 ciliated spores are aggregated together, forming a 

 rapidly-moving sphere. Of this the Pandorina 

 morum affords a good example (Fig. 13, PI. 1), in 

 which each spore possesses two cilia. But the 

 most remarkable of this kind of moving plant is 

 the Volvox globator (Fig. 14, PI. 1). This beautiful 

 moving plant was at one time thought to be an 

 animalcule, but it is now regarded as a true plant. 

 It consists of a large number of spores, or cells, each 

 having two cilia, and connected together by a deli- 

 cate network of threads. In the interior of this 

 moving sphere are seen smaller globular masses, of 

 a dark -green colour, which are the young of the 

 volvox, which have not yet developed the network 

 by means of which their spores are separated, and 

 their ciliated ends presented to the water, and by 

 means of which their movements are effected. 



Another form which is now regarded as a 

 locomotive plant is the Euglena viridis (Fig. 15, 

 PI. 1). It is often found in prodigious numbers, 

 giving to water the appearance of green-pea soup. 

 When placed under the Microscope, it frequently 

 presents a red speck, or point, at one end, and 

 an elongated tail at the other. The red spot 

 has been regarded as an eye ; but if it is watched, 

 it will be found the red colour will often extend 

 from the red spot to the rest of the body ; and 

 it. is probable that the red colour is only a change 

 in the condition of the chlorophyle contained in its 

 interior. Amongst this class of plants it is not 

 unfrequent for the chlorophyle to assume a red 

 colour at certain stages of its growth. 



