THE RELATIONSHIP OF BACTERIA 



125 



Relationship to Protozoa. Bacteria also possess some 

 points of resemblance to certain single-celled animals belong- 

 ing to the protozoa. There is a species, Polytomauvella, 

 belonging to the order of Flagellata, which is ovoid or bacil- 

 lus-like in shape and which possesses polar 

 flagella. The number of these flagella is 

 quite definite for the species. There are 

 other species which possess a tuft of flagella 

 at the poles similar to the lophotrichous 

 and amphitrichous bacteria. Still other 

 forms possess a pulsating vacuole which 

 suggests a resemblance to a structure of 

 that nature in Beggiatoa. The cell wall in 

 certain species of bacteria is very similar 

 to the cell wall of certain Sporozoa which 

 belong to the protozoa (Fig. 38). 



The process of encystment, which takes 

 place when some of these forms of pro- 

 tozoa come in contact with unfavorable 

 surroundings, closely resembles the forma- 

 tion of endospores by some species of bacteria. In distinct 

 contrast to the bacteria, the protozoa, and particularly the 

 flagellata, possess a well-defined nucleus. Some of the pro- 

 tozoa are quite similar to the fungi and particularly the 

 yeasts, as, for example, Trichomonas intestinalis and Tri- 

 chomonas vaginalis. 



The Myxomycetes, or slime molds, bear many points of 



FIG. 38. Dimorpha 

 radiata. Showing 

 nucleus, contrac- 

 tile vacuole, etc. 

 (Protozoon.) After 

 Schmidt and Weis. 



