FORM AND STRUCTURE OF MICROBES 51 



vessel of water one can see under the microscope motile 

 creatures, whose surface is furnished with cilia, whiplets or 

 flagella in vibration ; these are the infusoria, some with flagella, 

 others with cilia. Sleeping sickness is caused by a trypanosoma^ 

 a flagellate protozoon found at certain times in the blood, 

 in the lymphatic glands of the neck and in the cerebro-spinal 

 fluid. These protozoa resemble minute flattened worms in 

 the interior of which there are two nuclei, one large, one 

 small ; on one side there is an undulating membrane bordered 

 by the flagellum, which is continued beyond the anterior end. 



FIG. 15. -Trypanosomes and blood corpuscles. 



The trypanosomes multiply by longitudinal division beginning 

 with the nucleolus and continuing through the flagellum, the 

 large nucleus, and the protoplasm. There is a possibility that 

 sexual reproduction exists. 



There is often found in the intestine of rabbits an animal 

 parasite which passes through a complicated series of different 

 forms ; it possesses a cycle of evolution, one portion in the 

 rabbit, one portion outside. This parasite is a coccidium 

 belonging to the class of sporozoa. The microbe of malaria 

 is a parasite of the blood corpuscles, a haematozoon, which has 

 for long been regarded as related to the coccidia, but which 



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