46 BEITISH FRESHWATER BHIZOPODA. 



Ill the ooze of ponds ; amongst aquatic vegetation ; 

 also in marshes and bog-pools ; abundant and univer- 

 sally distributed. 



Amoeba proteus was first described and figured 

 by Rosel, under the name Der Ueine Proteus, in his 

 * Insecten-Beliistigung ' (Recreations amongst Insects), 

 1755. This was the first introduction to Naturalists 

 of the Rhizopoda as a class. Three years later Linnaeus 

 embodied it in his ' Systema Naturae,' ed. 10, calling it 

 Volvox chaos; Pallas (1766) changed the name to 

 Volvox proteus; and subsequently, under a variety of 

 designations, each representing, no doubt, some one of 

 the many forms assumed by the organism, it figured 

 in the works of Continental authors. Ehrenberg, in 

 his ' Infusionsthierchen ' (1838), described the familiar 

 large form as Amoeba princeps, a name which it long 

 retained ; but Leidy, considering that A. princeps 

 Ehrenb., and Proteus diffluens Miiller the original Der 

 Heine Proteus of Rosel represented one and the same 

 animal, once more revised the nomenclature and 

 adopted the title Amoeba proteus, which is likely to be 

 retained. Leidy .remarks : " The specific name proteus 

 (in Volvox proteus of Pallas) appears the more appro- 

 priate, and would at the same time serve to perpetuate 

 the name given to the animal by its discoverer." 



Amoeba proteus, in one or more of its forms, must 

 be familiar to every student of pond-life. It is to be 

 found in all still ponds which contain healthy vegeta- 

 tion, either in the ooze at the bottom, about the older 

 stems and leaves of aquatic plants, or in masses of 

 floating algae. During active movement the pseudo- 

 podia are usually digitate, simple or branched, of 

 uniform thickness or tapering to a blunt apex ; and 

 the nucleus, which is invariably oval, is habitually 

 posterior, the contractile vesicle occupying a position 

 at no great distance behind it. Necessarily, however, 

 during rapid movement, when the animal changes its 

 line of march, forming pseudopodia first on one side, 

 then on the other, the nucleus and vesicle get widely 



