46J< OKIGINAL ARTICLES. 



diffused, on which the hue and opacity of the body depend; its central 

 portion seems to have an almost aqueous consistence, the granular 

 particles being seen to move quite freely upon one another, with every 

 change in the shape of the body ; but its peripheral portion is more 

 viscid, and graduates insensibly into the firmer substance of the 

 ectosarc. The ectosarc, which is perfectly pellucid, forms an almost 

 membranous investment to the endosarc ; still, it is not possessed of 

 such tenacity as to oppose a solution of its continuity at any point, 

 for the introduction of alimentary particles, or for the extrusion of 

 effete matter; and thus there is no evidence, in Amoeba and its 

 immediate allies, of the existence of any more definite orifice, either 

 oral or anal, than exists in other Ehizopods. It is asserted by 

 MM. Claparede and Lachmann, however, that an oral orifice does 

 exist in JPodostoma, a peculiar modification of the Amoeban type ; and 

 they think it not impossible that such an aperture may exist even in 

 Amceba, of which the lips might be exactly applied to one another, 

 as in Amphileptus, so as only to open for the ingestion of food. The 

 more advanced differentiation of the ectosarc and the endosarc of 

 Amoeba is made evident by the effects of re-agents. If, as Aiierbach has 

 shown, an Amceba radiosa be treated with a dilute alkaline solution, 

 the granular and molecular endosarc shrinks together and retreats 

 towards the centre, leaving the radiating extensions of the ectosarc 

 in the condition of coecal tubes, of which the walls are not soluble, 

 at the ordinary temperature, either in acetic or mineral acids, or in 

 dilute alkaline solutions ; thus agreeing with the envelope noticed 

 by Cohn as possessed by Paramecium and other ciliated Infusoria, 

 and with the containing membrane of ordinary animal cells. A 

 nucleus is always distinctly visible in Amceba, adherent to the inner 

 portion of the ectosarc, and projecting from this into the cavity 

 occupied by the endosarc ; when most perfectly seen, it presents the 

 aspect of a clear flattened vesicle surrounding a solid and usually 

 spherical nucleolus ; it is readily soluble in alkalies and first expands 

 and then dissolves, when treated with acetic or sulphuric acid of 

 moderate strength ; but when treated with diluted acids it is rendered 

 darker and more distinct, in consequence of the precipitation of a 

 finely granular substance in the clear vesicular space that surrounds 

 the nucleolus. 



In all these particulars, therefore, the Amcebina present a nearer 

 approach to Ineusokia than is discernible among other Ehizopods ; 

 and hence it was not without good reason that Prof. Muller desig- 

 nated them " Infusorial Ehizopods." They tend towards Infusoria, 

 also, in their higher locomotive powers, obtaining their food by 

 actively going in search for it, instead of entrapping it and drawing 

 it into the substance of their bodies by the agency of their extended 

 pseudopodia. In fact, the pseudopodia are here very different organs 

 from those of either Beticiilaria or Badiolaeia, being rather lobate 

 extensions of the body itself, than appendages proceeding from its 

 surface-layers. They lire few in number, short, broad, and rounded ; 



