THE AMOEBAE 



131 



amoeboid stage is relatively small. The 

 cysts are uninucleate, with a smooth wall. 



Triiuastigamoeba philippinensis Whit- 

 more, 1911 was first found in human 

 feces. Bovee (1959) rediscovered it in 

 sewage-seepage into a spring in Florida 

 and redescribed it. According to Whit- 

 more (1911), the flagellate stage has 3 

 (occasionally 2 or 4) anterior flagella and 

 measures 16 to 22 by 6 to 8 j:i . Bovee, 

 however, found that there are actually 4 

 anterior flagella which arise in pairs from 

 2 basal granules adjacent to the nucleus. 

 The flagella lie in an anterior, gullet-like, 

 cylindrical invagination and extend 20 to 

 25 [x beyond it. According to Bovee, the 

 fully formed flagellate stage is 17 to 20 |i 

 long, its larger rear end is 6. 5 to 7. 5 ji 

 in diameter, the narrower anterior end 

 is 4. 5 to 5. 5|U in diameter and the anter- 

 ior pocket is 1 ji deep. 



The amoeboid stage was said by 

 Whitmore (1911) to be 16 to 18 ii in diam- 

 eter. Bovee (1959) said that it is 12 to 

 18fi in diameter when at rest and 30 to 

 40 (i long and 14 to 20 )i wide during rapid 

 locomotion. It moves quickly by means 

 of rapidly-extruded eruptive waves at its 

 frontal margin. It feeds principally on 

 bacteria and has a contractile vacuole 

 which is formed by the union of several 

 small vacuoles in about 2 minutes. The 

 cysts are oval to subspherical. Whitmore 

 (1911) gave their dimensions as 13 to 14 

 by 8 to 12 fi. 



FAMILY AMOEBIDAE 



Members of this family are free-living 

 or coprophilic. They have no flagellate 

 phase. This family contains, besides 

 Amoeba and a number of other free-living 

 genera, several coprophilic species and 

 one which can produce disease with a little 

 human help. 



Genus ACANTHAMOEBA 

 Volkonsky, 1931 



These are relatively small amoebae 

 without well developed ectoplasm. The 

 nucleus is vesicular, with a large endo- 



some. During mitosis, the nuclear mem- 

 brane disappears at prophase. The mi- 

 totic figure at the end of metaphase is a 

 straight or concave spindle with sharply 

 pointed poles. The cysts are angular and 

 polyhedric, with 2 membranes, the outer 

 one being highly wrinkled and mammillated. 



Acanthamoeba hyalina (Dobell and 

 O'Connor, 1921) Volkonsky, 1931 (syn. , 

 Hartnianiiella hyalina) is a common copro- 

 philic form. It occurs in soil and fresh 

 water and is easily cultivated from old 

 human and animal feces. Its trophozoites 

 are 9 to 17 fi in diameter when rounded. 

 It has a single contractile vacuole and a 

 single vesicular nucleus with a central 

 endosome and peripheral chromatin. The 

 cysts are spherical, 10 to 15fi in diam- 

 eter, with a thin, smooth inner wail and 

 a thick, wrinkled, brownish outer wall. 



Walker (1908) described an amoeba 

 from the intestinal tract of the turkey in 

 Massachusetts under the name A»ieba 

 gallopavoiiis which Chatton (1953) listed 

 as Acanthamoeba gallopavonis Walker. 

 It had angular cysts and may be synony- 

 mous with A. hyalina. 



Acanthamoeba has occasionally been 

 encountered as a contaminant of tissue 

 cultures and, because of its pathogenicity 

 on injection and the resistance of its cysts 

 to virucidal agents, it is a potential haz- 

 ard in vaccines prepared from viruses 

 grown in tissue culture. 



Jahnes, Fullmer, and Li (1957) and 

 Culbertson, Smith and Minner (1958) 

 isolated an Acanthamoeba sp. from tissue 

 cultures of trypsinized monkey kidney 

 cells. The latter first recognized the 

 amoebae in the lesions of monkeys which 

 had died following inoculation of tissue 

 culture fluid thought to contain an unknown 

 virus but later shown to contain only 

 Acanthamoeba. Following intracerebral 

 and intraspinal inoculation into cortison- 

 ized monkeys, the amoebae caused ex- 

 tensive choriomeningitis, destructive 

 encephalomyelitis and death in 4 to 7 days. 

 Following intracerebral inoculation into 

 mice, they caused destructive encepha- 

 litis and death in 3 to 4 days. Following 

 intranasal instillation into mice, they 



