OF THE PEOTOZOA. RHIZOPODA. 209 



thick. This intestinal cavity, he affirmed, communicated with the cell in 

 front, and the one next behind it by a narrower canal — the siphon, — and 

 that in this manner a sort of continuous moniliform intestine was produced, 

 extending from the primary to the penultimate cell. He adds that, after the 

 solution of the shell of Nonionina Germanica by dilute acid, various sihcious 

 Infusorial shells could be seen within this digestive tube, as far back in the 

 animal as the fii^st chamber. Moreover, he was fortunate enough to be able, 

 after the dissolution of the shell of Rotalia by acid, and by proceeding very 

 gradually, to set fi'ee an internal, spiral, jointed body, the segments of which 

 were strung together in Nonionina by one, and in Geojoonus by fi^om 18 to 

 20 tubes (siphons) ; strong acids destroyed the shell so rapidly that the con- 

 tained delicate body became broken up into many insignificant fragments. In 

 none did he succeed in introducing coloured food. This digestive apparatus 

 others have sought in vain in the Foyximinifera. The spiral articulate body 

 extracted by the Berlin naturalist from the shell, was undoubtedly nothing- 

 more than the soft animal contents, somewhat acted on by the acid, such as 

 Schultze has pictured from the cavity of a Miliola (XXI. 24). 



Eespecting the penetration of food to the primordial chamber, which Ehren- 

 berg imagined he had seen in Nonionina, Schultze observes that, among the 

 many beings he has examined, he has not detected nutritive matters fiu'ther 

 back than the second or third cell. 



The substances received from without, after ha\dng served their purpose 

 within the gelatinous body of Ehizopoda, make their way outwards and 

 escape from any part of the siu-face, — an anus being, like the mouth, pro- 

 duced temporarily, at any point whatever, where matters present themselves 

 for discharge. 



The materials taken within the body of Rhizopods are most heterogeneous ; 

 no selecting power being displayed by the animals, various Ciliated Protozoa, 

 fragments of the filaments and spores of Algae, frustules of Diatomece and 

 Desmidiece, even Rotatoria, fall a prey : but along with these, from which 

 nutriment may be extracted, are other substances which can be supposed to 

 serve no useful purpose ; such are particles of sand, morsels of woollen and of 

 cotton tissues, and the like. The introduction of particles indiscriminately 

 is explicable from the mode in which they are eaptm^ed by the filamentary 

 arms, which seem to act in a prehensile manner, on feeling the contact of any 

 foreign object, be that what it may. 



Dujardm threw doubts upon the nutritive purpose of the solid objects 

 swallowed, and supposed the act of nutrition consisted in the simple imbibition 

 or endosmosis of fluid from without. " It is," he writes, ^' difiicult of belief 

 that these included particles, by reason of their consistence and the unalter- 

 abihty of many of them, can serve to nourish the Amoebce ; yet, whilst admit- 

 ting that they are nourished by absorption, I would not deny that they may 

 find means of stiU more readily appropriating nutritive materials, by swallow- 

 ing various foreign bodies, and by so increasing their absorbent surface." The 

 evidence of direct observation, hov\^ever, is in favour of the conclusion that 

 the substances received within the simple animal mass actually afford ma- 

 terials for its nutrition. The contents are ever changing and making their 

 exit from it ; and an act of digestion or of solution is perceptible — slow, indeed, 

 even when soft Ciliated Protozoa are the subjects. Thus animalcules, when 

 within the sarcode mass, are first compressed into small balls ; the distinct- 

 ness of their parts then fades, and they are presently converted into small 

 gelatinous globules, which in due course disappear, from amalgamation with 

 the enclosing substance. Where the included body consists partially of 

 insoluble material, this remains behind in the form of fine granules, or, in 



p 



