4 COMPARATIVE ANATOMY chap, i 



Protista, consisting of the simplest organisms. But there is also no 

 sharp line of demarcation between the Protista on the one side and 

 animals and plants on the other. Some Protista are, chiefly by their 

 method of nutrition, more nearly related to plants, others to animals. 

 The latter are called Protozoa, in contradistinction to all other animals, 

 "which are classed as Metazoa. 



THE FIRST EACE OR PHYLUM OF THE ANIMAL KINGDOM, 



PROTOZOA. 



Systematic Review. 



Class I. Monera. 



Simplest organisms. Small masses of protoplasm of varied changing form, in 

 which till now no nuclei have been demonstrated. Locomotion and ingestion of 

 food by means of blunt (amosboid) or long and fine processes (pseudopodia). Repro- 

 duction by fission and gemmation. All Monera live in water. Frotanueba, 

 Myxodietion, Protomyxa. 



Class IL Sarcodina. 



Unicellular organisms, with nucleus or nuclei. Locomotion and ingestion of food 

 by means of filose non-vibrating processes of varying length (pseudopodia). Repro- 

 duction by fission or gemmation. 



Sub-Class I. Amoebina. 



Naked or shelled Sarcodina of changing shape. Locomotion and ingestion of 

 food by means of streaming of the body and the formation of processes mostly short 

 and lobate. Contractile vacuoles generally present. Amceba (Fig. 1), Arcella 

 (Fig. 2, 0), Difflugia (Fig. 2, D), Quadrula (Fig. 2, A), Myalosphenia (Fig. 2, B). 



Sub-Class II. Ehizopoda. 



Sarcodina whose protoplasm secretes a very variously -shaped chitinous, generally 

 calcareous, shell, which is at first imiaxial. Locomotion and ingestion of food by 

 means of pseudopodia, which frequently fuse with one another, often in a reticular 

 manner. Contractile vacuoles generally absent. 



A. Imperforata. 



Shells of one chamber or more, not perforated by fine pores, but havino- one or 

 two larger apertures through which the protoplasm and the pseudopodia pass out. 

 Miliola (Fig. 3, CO, Litnola, Gromia (Fig. 3, A). 



B. Perforata. 



Shells of one chamber or more, perforated by fine pores for the passage of the 

 pseudopodia. Globigerina, Rotalia ( Fig. 3, B). 



