826 PARASITES OF THE DOMESTIC ANIMALS 



Control. — The sick animals should be at once separated from those 

 which are apparenth' not infected and the pens and runs subjected to 

 thorough cleaning up and disinfection as recommended in other forms 

 of poultry parasitism. It is important that the yards be kept dry and 

 that the droppings be promptly removed and so disposed of that thej^ 

 cannot be a source of reinfection. 



Treatment is of little value. As paUiative, intestinal antiseptics, as 

 eucalyptus or listerine, may be tried. 



Amebic Dysentery in Man. — This is a disease occurring in tropical 

 and subtropical, and at times in temperate regions, the cause of which 

 is regarded bj' pathologists to be an ameba, — Entamha histolytica. Ar- 

 tificial production of amebic dysentery has been brought about in dogs 

 and cats by rectal introduction of human feces containing the amebae. 

 It has been shown in such cases that the parasites invade the glandular 

 crypts of the intestinal mucosa from which they penetrate to the sub- 

 mucosa and give rise to a hemorrhagic enteritis. In its further course the 

 affection is accompanied by thickening and destructive ulceration of the 

 mucosa. 



The diagnosis of amebic dysentery is by demonstration of the ame- 

 bae in the stools. They may be differentiated from Entameba coli, an 

 intestinal species which is considered to be a harmless commensal, by 

 their definite and relatively firm ectoplasm which gives a rigid character 

 to the pseudopodia, enabling the parasites to force their way between 

 the epithelimn of the crypts and into the more deeply lying tissues. The 

 nucleus of E. histolytica varies in shape and position with the activities 

 of the cytoplasm; it has little chromatin, and no nuclear membrane is 

 apparent. The nucleus of E. coli is usually spherical and shows little 

 change in position. 



Class II. Flagellata (Mastigophora) 



Protozoa (p. 311). 



As has been stated, there are certain forms among the Rhizopoda in 

 which the pseudopodia disappear from time to time to be replaced by 

 one or more flagella; in other cases there maj^ even be permanent fla- 

 gella contributing to the pseudopodia in their function of locomotion and 

 prehension. Such flagellate rhizopods are transitional to the Flagellata 

 and serve to prevent the drawing of a sharp line of demarcation between 

 the two groups based upon the possession of flagella. In general it maj^ 

 be said of the Flagellata that they are permanently flagellate, the fla- 

 gella serving for locomotion and feeding. Thej' exhibit a great diversity 

 of form which is to a large extent correlated with the number and loca- 

 tion of the flagella. A degree of complexity' is exhibited by some free- 

 living forms in the possession of a mouth and cytopharynx. but all par- 



