ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 209 



protoplasmic filaments at different parts of the body. There are 

 three processes of equal breadth throughout which stand out from the 

 body, sometimes in one place, sometimes in another, and bend to and 

 fro as if feeling about, often curved, but generally pretty straight. 

 At first it seemed that these pseudopodia did not, as in other Amoebce, 

 spring from the protoplasmic body in the shape of fingers gradually 

 becoming thinner, but that small conical elevations of the body served 

 as their base, and that they rose from these with a distinctly marked 

 separation. When they were very numerous they gave the Amceba a 

 very peculiar appearance (PI. III. Fig. 1). 



With a Hartnack No. X. (or Seibert's homogeneous immersion) 

 the whole Amoeba proved to be enveloped by a fine layer of denser 

 substance, a membranaceous cortical layer which causes the periphery 

 of all its humps and processes to aj)pear distinctly double-contoured. 



Directly within this firmer envelope lies the soft internal sarcode- 

 mass. If a pseudopodivim is to be pushed forth, the enveloping layer 

 must first be broken through. This, however, oifers some resistance, 

 and is consequently pushed out in a conical form. An aperture is 

 broken through at the apex of the cone, and the sarcode issues in the 

 form of a thin filament (Fig. 8). The retraction of the pseudopodium 

 was very distinctly observed, after which a new one frequently issued 

 from the same cone. 



The pseudopodial cones have a very constant form, and although 

 they can obliterate themselves again completely, this does not always 

 take place after the retraction of the pseudopodium ; but very 

 frequently the elevation remains, and a small crater seems to have 

 been formed where the pseudopodium was emitted (Fig. 2 Jc). One 

 specimen had many cones, but all without processes (Fig. 4 »•), 

 nevertheless they persisted without alteration for a considerable 

 time. 



Whether the pseudopodia act as tactile organs or bring in food, 

 cannot be definitely stated. The former, however, appears to be more 

 probable, for in the interior are nutritive materials, such as diatoms, 

 algsB, &c., much too large to be capable of penetrating through tlie 

 narrow aperture of the cone. 



At any rate the animal, notwithstanding its firmer enveloping 

 layer, is able to take in solid materials. Moreover, we know very 

 nearly allied forms such as A. verrucosa, which are destitute of these 

 organs, and nevertheless take in such nutritive bodies. Sometimes it 

 appeared as if a slow locomotion was effected by means of the 

 pseudopodia, but only to very inconsiderable distances. 



In advancing, A. tentaculata employs no special organ any more 

 than its allies which possess a firm cortical layer. The humps and 

 folds gradually disappear, the pseudopodia are for the most part 

 drawn in, and with them the cones, and after the surface has become 

 smooth, there commences a steady flow in one direction, exactly in 

 the same manner as has long beeu known in A. verrucosa, although 

 much slower. In the latter this stage was for a time regarded as 

 forming a distinct species under the name of A. quadriUneata. 



The longitudinal folds which gave the name to the latter, and 

 Ser. 2.— Vol. II. P 



