Knowledge of the Amoebse. 1 09 



a conical form*. An aperture is broken through at the apex 

 of the cone ; and the sarcode issues in the form of a thin hla- 

 ment. Fig. 8 may serve to illustrate this process ; in it we 

 see distinctly the thin cortical layer (6) of the pseudopodial 

 cone, and also within it the central substance (m), which is 

 pushed forth as a pseudopodiuni {jp) at the apex. 



I succeeded in observing very distinctly the retraction of 

 the pseudopodium, after wliich a new one frequently issued 

 from the same cone. I also believe that I have often seen 

 the issue of two pseudopodia simultaneously. 



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 pseudo- 

 podium ; but very frequently the elevation persists afterwards, 

 and a small crater seems to have been formed at the spot 

 where the orifice for the pseudopodiuni was situated (see fig. 2, 

 Ti). I once found a specimen on which there were many 

 pseudopodial cones, but all without processes (fig. 4, h) ; 

 nevertheless they persisted, without alteration, for a consider- 

 able time. 



I said above that the pseudopodia which are produced in 

 this w^ay bend slowly to and fro, a movement wliich they have 

 in common with those of other Amcehce. Whether they act 

 as tactile organs, or are destined to bring in food, I cannot 

 definitely state. The former, however, appears to me more 

 probable ; for we find in the interior nutritive materials, such 

 as Diatoms, Alga3, &c., which are much too large to be 

 capable of penetrating through the narrow aperture of the 

 pseudopodial cone f. 



At any rate the animal, notwithstanding its firmer envelop- 

 ing 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 to me 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 

 form in which we have hitherto considered it characterizes 

 only the resting state of the Amoeba. We soon see movement 



* Conical elevations have also been described in rodostoina filicjerum. 

 It is even said that a sort of buccal aperture occurs in them ; but this 

 requires conlirmation. At any rate, they may be referable to the struc- 

 tures before us. Moreover protrusions of similar appearance may very 

 probably occur in other Amccbce. (iSee also Auerbach, loc. cit, tig. \b.) 



t Somewhat as in Podostoma. 



