234 ANIMAL PARASITES 



circumferential cilia. In others a special muscular segment 

 of the body may exist. The suctorial tubes act also for motion 

 at times. In most protozoa two layers can be seen the ectosaro, 

 and endosarc. The ectosarc originates the movement, is concerned 

 in the ingestion and excretion of food, and the respiration. The 

 endosarc, which circulates slowly, is mainly for digestive purposes. 

 In it are ferments, crystals, food particles (seen in the food vacu- 

 oles), oil globules, gas, and pigment granules. 



Flagella and suctorial tubes in protozoa that have them 

 belong to the ectosarc. Skeletal tissues, shells, etc., also belong 

 to this layer. 



The food consists of bacteria, smaller animals, algae, and animal 

 waste. 



Propagation is effected by direct cell division, beginning in the 

 nucleus, by cell budding or by a complicated course of sporulation 

 which may be sexual or asexual. Sometimes division, or budding, 

 occurs rapidly without the segments separating, leading to the 

 formation of protozoal colonies, or swarm spores. 



In the case of the malarial plasmodia, asexual development, 

 (schizogony) takes place in man's blood, while the sexual develop- 

 ment (sporogony) takes place in the mosquito. Protozoa are 

 found in salt and fresh water, in damp places, and in animals as 

 parasites. 



Since the zoological classification has been given and may 

 used for reference to larger works, the various pathogenic proto- 

 zoa are given separately without direct reference to their sys 

 tematic classification. 



There are but two Rhizopods that are parasitic and pathogenic 

 to man. The only one of these of any import is the Amoeba. 



AMCEBA DYSENTERIC OR ENTAMCEBA 

 HISTOLYTICA 



This is a pear-shaped roundish body from .008 to .05 mm. ii 

 diameter. The ectosarc is easily discernible in the pseudopodia, 



