CHAPTER II 



SPILERELLA AND EUGLENA I MONADS AND BACTERIA 

 DIFFERENCES BETWEEN ANIMALS AND PLANTS- 

 SAPROPHYTES 



THE rain-water which collects in puddles, open gutters, 

 &c., is frequently found to have a green or red colour. 

 The colour is due to the presence of various organisms 

 plants or animals one of the commonest of which is 

 Sphcerella (or, as it is sometimes called, Hcematococcus or 

 Protococcus) pluvialis. 



Like Amceba, Sphaerella is so small as to require a 

 high power for its examination. Magnified three or four 

 hundred diameters it has the appearance (Fig. 68, A) 

 of an ovoidal body, somewhat pointed at one end, and 

 of a bright green colour, more or less flecked with 

 bright red. 



Like Amoeba, moreover, it is in constant movement, 

 but the character of the movement is very different in 

 the two cases. An active Sphaerella is seen to swim 

 about the field of the microscope in all directions and 

 with considerable apparent rapidity. We say apparent 

 rapidity because the rate of progression is magnified to 

 the same extent as the organism itself, and what appears 

 a racing speed under the microscope is actually a very 



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