1858.] on the Tthizopod Type of Animal Life, 499 



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 

 are composed, not being invested (any more than the sarcode of 

 the body) by any limiting membrane, coalesce with each other and 

 with it ; and thus the particle which has been entrapped becomes 

 actually imbedded in the gelatinous mass, ^d gradually passes 

 towards the central part of it, where its digestible portion under- 

 goes solution, the superficial part of the body with its pseudopodial 

 prolongations in the meantime recovering its previous condition. 

 Any indigestible portion, as the shell of an Entomostracan, or the 

 hard case of a Rotifer, finds its way to the surface of the body, and 

 is extruded from it by a process exactly the converse of that by 

 which it was drawn in. 



If, now, it be asked in what consists the peculiar animality of 

 beings thus destitute of every feature that we are accustomed to 

 associate with the idea of an animal, — that is, if it be enquired 

 what are the characters by which they are distinguished from 

 vegetable organisms of equal simplicity, — the physiologist cannot 

 with confidence reply that sufficient evidence is afforded by the 

 movements of the Amoeba and Actinophrys ; since among the lowest 

 Plants there are many, which, at least in certain stages of their 

 lives, are endowed with yet even greater activity. A more positive 

 and satisfactory distinction lies in the nature of their aliment, and 

 in the method of its introduction. For whilst the protophyte obtains 

 the materials of its nutrition from the air and moisture that sur- 

 round it, and possesses the power of detaching oxygen, hydrogen, 

 carbon, and nitrogen from their previous binary compounds, and of 

 uniting them into ternary and quarternary organic compounds 

 (chlorophyll, starch, albumen, &c.), the simplest protozoon, in com- 

 mon with the highest members of the animal kingdom, seems* 

 utterly destitute of any such power, and depends for its support 

 upon organic substances previously elaborated by other living beings. 

 Further, whilst the protophyte obtains its nutriment by simple 

 imbibition, the protozoon, though destitute of any proper stomach, 



