300 



PLASMODROMATA AND SARCODINA 



II. With a flagellate stage in the life-cycle: — 



(a) Flagellate forms divide^ — Genus 4, Pammceba 



Schaudinn, 1896. 

 (&)_^Flagellate forms do not divide: — 



1. Uniflagellate^ — Genus 5, Craigia Calkins, 1912. 



2. Biflagellate • — Genus 6, Naegleria Alexeieff, 



1912; mewfi'^??;?^ Calkins, 1912. 



3. Triflagellate— Genus 7, Trimastigamcela Whit- 



more, 191 1. 



B. Parasitic, commensal, or pathogenic : — 



I. Contractile vacuoles numerous; cysts give rise to 



gametes — Genus 8, Entamoeba Leidy, 1879. 



II. Contractile vacuoles absent; cysts not known to give 



rise to gametes — Genus 9, Loeschia Chatton and 

 Lalung-Bonnaire, 1912. 



The principal species of the genus Amoeba are the type A . proteus 

 (Pallas, 1766), A. vespertilio Penard, 1902, A. verrucosa Ehrenberg, 



1838, and A. terricola Greeff, 1892, 

 but the last two may be the 

 same species. 



The type species of Naegleria 

 is N. punctata Dangeard, 191 0, 

 found in pond water and infusions. 



Trimastigamoeba has only one 

 species, T. philippinensis Whit- 

 more, found in tap water in 

 Manila. 



Entamoeba has as its type 

 species E. hlattcB Biitschli, 1878, 

 described in detail by Mercier in 

 Fig. 48.— Cyst of Amoeba proteus 1909 and 1910, who says that the 

 (Pallas, 1766). (After Carter.) gamete-forming cysts give rise 



to minute uninucleate gametes, 

 which conjugate outside the cyst, while the copula develops directly 

 into the trophozoite. This is very different from what is known 

 concerning the life-history of Loeschia. 



As the type genus is Amoeba, and its type species Amoeba proteus 

 (Pallas, 1766), it is interesting to know its life-cycle, which is but 

 little understood at present. 



Miss Carter has, however, studied encystment, while simple division is 

 fully established and schizogony is doubtful. 



The precystic stage is characterized by the Amoeba becoming sluggish, 

 clearing its body of debris, and exuding a slimy mucus, which causes surround- 

 ing detritus to adhere to it, and so to form an outer protecting covering, inside 

 which two membranous cyst walls, separated by fluid, are formed. The cysts 

 measure 70 to 140 microns in diameter, and are found in England from late 

 December to the middle of March. They are spherical and without means of 

 attachment. 



