GENERAL ZOOLOGY 



Fig. 8.7. Skeletons of representative foraminiferans (A) 

 and radiolarians (B). (Photographs courtesy General 

 Biological Supply House, Inc.) 



cysted form, the four nuclei are produced by two nuclear divisions, the fore- 

 runners of cytoplasmic divisions which occur immediately after excystment. 

 From each cyst, eight uninucleate individuals are ultimately produced, each 

 of which subsequently grows into the large, active trophozoite form. 



Once regarded as a tropical disease, amoebiasis is now known to be dis- 

 tributed throughout the world, even to the Arctic Circle. Infections are of 

 common occurrence wherever crowded conditions are combined with in- 

 adequate sanitary facilities; such situations may lead to the outbreak of 

 epidemics. With increasing travel to and from parts of the world where the 

 incidence of the disease is high, amoebiasis may cause increasing concern in 

 this country. Fortunately, methods of prevention are well known, although 

 not always practiced; however, curative treatment is still a problem. 



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