406 MICROSCOPIC FORMS OF ANIMAL LIFE. 



described as a minute mass of " sarcode," presenting scarcely 

 any evidence of distinct organization, even of the simplest kind ; 

 for, as in the lowest forms of Vegetable cell (§ 148), there is not 

 even a complete differentiation between the cell-wall and the 

 cell-contents; the former not being composed of a distinct 

 membrane, though obviously possessing more consistence than 

 the latter, which are semi-fluid. A contractile vesicle (or rather, 

 perhaps, a " vacuole") may be observed in some part of the body, 

 which pulsates at tolerably regular intervals; and "vacuoles" or 

 clear spaces are seen, surrounding the alimentary particles which 

 have been received into the midst of the jelly-like substance. 

 However inert and shapeless this minute body may be when 

 first noticed, its possession of vital activity is soon made appa- 

 rent by the movements which it executes, and by the changes of 

 form which it undergoes ; these being, in fact, part of one and 

 the same set of actions. For the shapeless mass puts forth one 

 or more finger-like prolongations, which are simply extensions 

 of its gelatinous substance in those particular directions ; and a 

 continuation of the same action, first distending the prolonga- 

 tion, and then (as it were) cari-ying the whole body into it, causes 

 the entire mass to change its place. After a short time another 

 prolongation is put forth, either in the same or in some different 

 direction ; and the body is again absorbed into it. These changes 

 seem to be connected with a movement of the semi-fluid particles 

 in the interior of the mass, of which a current may be observed 

 to " set" in the direction wherein the protrusion is about to take 

 place, before ^ the surface shows any projection. When the 

 ci-eature, in the course of its progress, meets with a particle 

 capable of affording it nutriment, its gelatinous bodj^ spreads 

 itself over or around this, so as to envelope it completely ; and 

 the substance (sometimes animal, sometimes vegetable) thus 

 taken into this extemporized stomach, undergoes a sort of diges- 

 tion there, the nutrient material being extracted, and any indigesti- 

 ble part making its way to the surface and finally being (as it were) 

 squeezed out. Of the mode of reproduction of J.mcBJa, nothing is 

 yet known, save that it undergoes multiplication by self-division, 

 very much in the manner of the Protophytes, and that portions 

 separated from the jelly-like mass, either by cutting or teai-ing, 

 can develope themselves into independent beings. Consequently, 

 as we are quite in the dark respecting the sexual operation, 

 which (as all analogy would lead us to believe) must take, place 

 at some period of its life, it cannot be said that we are 

 acquainted with more than one phase of its existence ; and it is 

 quite possible that, after many repetitions of the process of multi- 

 plication by self-division, some entirely new form may present 

 itself, of which the Amoeba is (as it were) the larva. The com- 

 pletion of the life-history of this curious creature, therefore, is a 

 most worthy object of Microscopic inquiry ; and its abundance 

 in many situations should prevent this from being a matter of 



