324 



ANIMAL LIFE 



FIG. 363. Photograph from life of the mouth of 

 the lamprey eel sucked fast to a piece of glass. 

 Natural size. 



become the guests of 

 other fish whose blood 

 and mucus they suck 

 by attaching to their 

 sides. 



Parasitic Protozoa. 

 Among the Proto- 

 zoa, the commonest 

 parasites are the 

 Amoeba dysenterica, in- 

 habiting the intestine 

 of man and causing 

 one kind of dysentery; 

 the Plasmodium malarice, residing in the human blood 

 corpuscles and producing malarial fevers; the Opalina, 

 of which hundreds 

 are present in the 

 large intestine of 

 the frog, and the 

 Gregarina, abun- 

 dant in the alimen- 

 tary canal of the 

 earthworm, lob- 

 ster, and many 

 beetles. 



Parasitic Worms. 

 Of parasitic 

 worms there are 

 more than a hun- 

 dred species, most 

 of which live at the 



FIG. 364. The malarial parasite photographed 

 through a microscope magnifying one thousand 

 diameters. Two individuals are present in the 

 red blood corpuscles. 



