LESSON II 



H^EMATOCOCCUS 



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

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

 is due to the presence of various organisms plants or 

 animals one of the commonest of which is called Hcema- 

 tococcus (or sometimes Protococcus or Sphcerella) pluvialis. 



Like Amoeba, Hsematococcus is so small as to require a 

 high power for its examination. Magnified three or four 

 hundred diameters it has the appearance (Fig. 3, A) of an 

 ovoidal body, somewhat pointed at one end, and of a bright 

 green colour, more or less necked with equally bright red. 



Like Amoeba, also, it is in constant movement, but the 

 character of the movement is very different in the two cases. 

 An active Haematococcus is seen to swim about the field of 

 the microscope in all directions and with considerable appa- 

 rent rapidity. We say apparent rapidity because the rate 

 of progression is magnified to the same extent as the organ- 

 ism itself, and what appears a racing speed under the micro- 

 scope is actually a very slow crawl when divided by 300. 

 It has been found that such organisms as Haematococcus 

 travel at the rate of one foot in from a quarter of an hour 

 to an hour : or, to express the fact in another and fairer way, 



