GENUS ENDAMCEBA 235 



Fantham and Porter (1911) saw an amceba which they named 

 E. apis in the bee, Apis mellifica. It resembled E. coli. 



Genus Endamoeba Leidy, 1879. 



This genus was created by Leidy (1879) for an amoeba of the cockroach 

 (Periplaneta orientalis). It was named Amwha blattw by Biitschli (1878), 

 while Leidy gave it the name Endamoeba blattce. If it should be proved 

 that this amoeba of the cockroach belongs to the same genus as the human 

 forms to which Casagrandi and Barbagallo (1895) gave the name Entamoeba 

 coli, then the correct generic name for the human and other forms will be 

 Endamoeba, as many American writers maintain. Cockroaches, however, 

 harbour at least two amoebse, one of which undoubtedly belongs to the 

 genus Entamoeba. The other is Endamoeba blattce, which, according to 

 Mercier, has such a characteristic nucleus that a distinct genus is justified. 

 Thomson and Lucas (1926) have recently redescribed the amoeba. Their 

 description conforms entirely with Mercier's account of the morphology 

 of E. blatter. 



Endamoeba blattae (Biitschli, 1878). — This amoeba was studied by 

 Schubotz (1905), Janicki (1908, 1909), and later by Mercier (1910), who 

 has given the most detailed account of its structure and life-history. 

 E. blattcB lives in the intestine amongst the various nematodes, vegetable 

 and other protozoal organisms which are found there. It varies very 

 much in size, ranging from 10 to 120 microns in diameter (Fig. 110). The 

 average-sized forms measure about 50 microns. The general appearance 

 varies considerably with the quantity and nature of the food inclusions with 

 which the endoplasm may be packed. There is no marked distinction 

 between ectoplasm and endoplasm, but the cytoplasm, which is highly 

 vacuolated, contains smaller vacuoles near the surface than at the centre. 

 The movements are sluggish, and one or two blunt pseudopodia are 

 formed at a time. Sometimes the cytoplasm streams internally in a 

 peculiar manner, which gives the amoeba a striated appearance. There 

 is no contractile vacuole. 



The nucleus, which differs in many respects from the typical nuclei 

 of members of the genus Entamoeba, is an ovoid structure measuring 

 10 to 15 or even 20 microns in its longest diameter. It is limited by 

 a remarkably thick nuclear membrane, within which, even in the living 

 amoebae, can be distinguished two zones — a peripheral one consisting of 

 refringent granules, and a central one of an alveolar nature — the two 

 zones being separated by a layer of large chromatin granules. The 

 majority of the amoeba? have a single nucleus, but there occur forms 

 which are multinucleate. 



