PROTOZOA IN DISEASE 317 



The amebas are also classed with the Sporozoa, but it has not been 

 proven that all of the organisms which are classed as amebas form swarm 

 spores. The primary cause of malaria certainly belongs to the sporozoa. 

 Cytologists are gradually recognizing the fact that many of the so-called 

 single-celled organisms, such as ameba, paramecium, etc., are not as 

 simple in structure and in physiological activity as was generally supposed. 

 Many of these organisms contain highly complex cell constituents which 

 enable them to compete quite successfully in the struggle for existence, 

 with the highly complex multicellular organisms. 



1. Entamosba coli. Inhabits the large intestine. Probably harmless. 

 Amoeba belong here and not in the sporozoa. May be confused with 

 phagocytes. 



2. Entamceba histolytica. Causes entero-colitis and dysenteric ulcera- 

 tions. It is also found in abscesses of the liver. Occurs in tropical 

 countries, less common in temperate zones. 



3. Entamceba buccalis. Found in dental caries. Probably not patho- 

 genic. 



4. Entamosba undulans. Occurs in the intestinal tract. 



5. Leydenia gemmipara. Identity doubtful. Supposed to have a 

 causal relationship to carcinomatosis (cancer). 



II. FLAGELLATA. Motion due to flagellae. Some possess an undulatory 

 motion. Have been classed as bacteria (Spirillae). 



1 . Spirochcsta recurrentis (Spirillum obermeieri) . ' This is the organism 

 which causes relapsing fever. The disease is so designated because 

 after apparent complete recovery, one or more relapses invariably 

 follow. It is not a very fatal disease (4 per cent, of deaths) and is, so far, 

 rare in the United States. It is and has been very prevalent in parts 

 of Europe. The disease can be transmitted, by inoculation, to man, 

 monkeys, mice and rats. An immunity treatment has been attemp- 

 ted with some success. Most authorities class the organism as a 

 fungus (Spirillum). 



2. Spirochcsta Duttoni. This organism is the primary cause of the 

 South African tick fever (Tete fever), so-called because the carrier is a 

 species of cattle tick (Ornithodoras moubata). 



3. Spirochata Novyi. Said to be the cause of American relapsing fever. 



l The systematic position of the spirochaetes is still in dispute. They probably 

 belong to the animal kingdom. Note the tentative position given them by the com- 

 mittee on the classification of bacteria appointed by the Society of American Bacteri- 

 ologists. The fully life history of these orgaisms has not yet been worked out. What has 

 been described under the name Treponema (Spiroch&ta) pallidum is in all probability 

 the male generation of this organism, the female cells being irregular in outline and 

 found in the lymphocytes and in other body cells. 



