102 NATURE STUDY IN SCHOOLS. 



SYSTEMATIC ZOOLOGY FOR TEACHERS. 



BY 



C. J. Maynard. 



BRANCH PROTOZOA. 



Single-celled Animals. 



In this group the single cell is the chief character. 

 That is, as far as our knowledge now extends, all the ani- 

 mals contained in this group are of a simple primitive struct- 

 ure, consisting of what appears to be a single cell. This 

 cell usually, however, contains organs, but these are of an 

 exceedingly simple character. Propagation is by division, 

 perhaps after conjugation with another protozoa of the same 

 species, never by eggs. 



Most of these animals are so minute that they are quite invisible with- 

 out the aid of a microscope, although some living forms are large enough to 

 be seen by the naked eye, some being ti quarter of an inch in diameter, while 

 a number of fossil forms were much larger than this. 



It, may be well for the teacher to note that this single cell in zoology 

 and botany are, in a great measure, equivalent to the atom in chemistry, or 

 the molecule in physics. 



CLASSIFICATION OF PROTOZOA. 



The following classification gives an idea of the prin- 

 cipal groups in this branch with description of some typical 

 forms, all of which illustrate some point of advancement 

 over the lowest, or most primitive form 



PROVINCE MONERA. 



The most simple forms of all animal life are placed in this group. They 

 are simple drops of jelly without any apparent nucleus or contractile vesicle, 

 but some of them are very brightly colored. They have no fixed form, 

 but they are constantly changing by thrusting out long, slender portions of 



