A STUDY OF MIXED PROTOZOAN CULTURES 



A study of mixed protozoan cultures is introduced for the 

 purpose of illustrutinji; the great variety of forms and modes of 

 life of these minute organisms and that of providing an oppor- 

 tunity to gather first-hand information concerning them. A 

 further object in this study is that of furnishing an introduction 

 to the identification (classification) of animals through the use 

 of so-called "tables" or "keys." Such keys make use of the 

 important structural features wherein animals resemble or 

 differ from one another. The statements of characteristic 

 features are so contrasted that the problem becomes one of 

 deciding with which of two contrasting statements a given animal 

 agrees. 



Place a drop of the culture in the center of a glass slide. After 

 placing a cover glass upon the drop, study the culture with the 

 low power of the compound microscope. Note differences in 

 form, size, and -behavior of the individuals coming within the 

 field of the microscope. ]\Iove the slide so as to bring different 

 regions of the culture into the field. Such observations should 

 give one a general idea of the different kinds of protozoans pres- 

 ent, their means of locomotion, and noticeable peculiarities. 



After a short period the organisms will become less active, 

 enabling one to focus the microscope upon a single individual 

 for a detailed study which will reveal those peculiarities whereby 

 it may be distinguished from other kinds. Look for those charac- 

 teristics mentioned in the first statement of the key designated 

 by A. The contrasting (opposite) characteristics will be found 

 under AA in the same vertical column. When the characteris- 

 tics given either under A or AA fit those of the organism proceed 

 to the statement immediately following, and so proceed until 

 a name appears at the end of the statement. If the observations 

 are correct this name will be that of the group to which the 

 organism belongs. Reading both of the contrasting statements 

 will aid one in determining which is descriptive of the organism 

 in (juestion. 



Assistance in tiie identification of these organisms may l»e 

 gained through comparisons made with the accompanying figures. 



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