Dr. Carpenter on the Rhizopod Type of Animal Life. 75 



instruments whatever ; — a little particle of apparently homogeneous 

 jelly changing itself into a greater variety of forms than the fabled 

 Proteus, laying hold of its food without members, swallowing it 

 without a mouth, digesting it without a stomach, appropriating its 

 nutritious material without absorbent vessels or a circulating system, 

 moving from place to place without muscles, feeling (if it has any 

 power to do so) without nerves, multiplying itself without eggs, and 

 not only this, but in many instances forming shelly coverings of a 

 symmetry and completeness not surpassed by those of any testaceous 

 animals. 



As an example of this type of existence, the Amazba, a common 

 inhabitant of fresh waters, may be first selected. This may be 

 described as a minute mass of ft. sarcode," presenting scarcely any 

 evidence of organization even of the simplest kind ; for although 

 its superficial layer has a somewhat firmer consistency than the 

 semifluid interior, this differentiation does not proceed to the extent 

 of constituting even a body so simple as the "cell" of physiologists, 

 which consists of a definite membrane investing and limiting its 

 contents. Although at some times shapeless and inert, the Amoeba 

 at others is a creature of no inconsiderable activity. Its gelatinous 

 body extends itself into one or more finger-like prolongations ; the 

 interior substance transfers itself into one or other of these, dis- 

 tending it until the entire mass is (as it were) carried into it ; and 

 then, after a short time, another prolongation is put forth, either in 

 the same or in some different direction, and the body being again 

 absorbed into it, the place of the animal is again changed. When 

 the creature, in the course of its progress, meets with a particle 

 capable of affording it nutriment, its gelatinous body spreads itself 

 over or around this, so as to envelope it completely ; and the par- 

 ticle (sometimes animal, sometimes vegetable) thus taken into this 

 extemporized stomach, undergoes a sort of digestion there, the 

 nutrient material being extracted, and any indigestible part making 

 its way to the surface, and being finally (as it were) squeezed out. 

 The Amoeba multiplies itself by self- division ; and portions separated 

 from the jelly-like mass, either by cutting or tearing, can develope 

 themselves into independent beings. 



Nearly allied to this is another curious organism, on which the 

 attention of many eminent microscopists has been recently fixed. 

 This creature, the Actinophrys, has a body whose form is more 

 constantly spherical, but extends its sarcode into radiating filaments 

 of extreme delicacy, which are termed pseudopodia ; and it is by 

 the agency of these, rather than by the change of place of its whole 

 body (as in Amoeba), that it obtains its food. For when any small 

 free-moving animalcule or active spore of a vegetable comes into 

 contact with one of the pseudopodia, this usually retains it by 

 adhesion, and forthwith begins to retract itself; as it shortens, the 

 surrounding filaments also apply themselves to the captive particle, 

 bending their points together so as gradually to enclose it, and 

 themselves retracting until the prey is brought close to the surface 

 of the body. The threads of "sarcode " of which the pseudopodia 



