. Journal of experimental zoology. e made in the usual way by watching the forms from above. I used Difflugia acuminata, D. spirahs,Amoeba proteus, A. Umax, A. verrucosa, A. radiosa and severalsmall forms of Amoeba which I did not determine. Amoebaproteus was especially well suited to my purpose, as it was largeenough to be easily seen with the unaided eye. • Difflug I a Difflugia acuminata extends a slender pseudopod to its fulllength free in the water. That it is free is evident from itsmotions. The pseudopod then becomes attached at its tip (Fig. 6)and contracts, drawing the mouth of the sh
. Journal of experimental zoology. e made in the usual way by watching the forms from above. I used Difflugia acuminata, D. spirahs,Amoeba proteus, A. Umax, A. verrucosa, A. radiosa and severalsmall forms of Amoeba which I did not determine. Amoebaproteus was especially well suited to my purpose, as it was largeenough to be easily seen with the unaided eye. • Difflug I a Difflugia acuminata extends a slender pseudopod to its fulllength free in the water. That it is free is evident from itsmotions. The pseudopod then becomes attached at its tip (Fig. 6)and contracts, drawing the mouth of the shell up to the point ofattachment. A new pseudopod appears pari passu, generally Locomotion of Amcebce and Allied Forms 343 near the base of the first (Fig. 6), and increases in length as thefirst is contracted. The new pseudopod, which is fully extendedwhen the mouth of the shell reaches the point of attachment,swings into the fine of advance and becomes attached. Thecycle is then repeated. Figs. 6 and 8 show the position of the. Fig. 6. Diagram of Difflugia acuminata showing changes from one pseudopod to , a, a, a, a show points of attachment; b,b,b,, the new pseudopod at different stages of its formation.(The diagram was made with camera lucida by drawing the paper at right angles to the line ofadvance.) mouth and pseudopod at different stages in the change from onepseudopod to another. Fig. 7 shows four successive positions ofthe shell at the time when a pseudopod becomes attached, and alsothe lines of advance of the shell and of the tips of new pseudopodsas they form and are carried forward. That the pseudopodswhile free take no part in drawing the shell forward is evidentfrom the fisure. Often Difflugia acuminata apparently moves with a singlepseudopod, in which case the new pseudopod is extended directly 344 Oris P. Dellniser over the tip of the old. I obtained evidence to prove this from aspecimen in which the second pseudopod appeared at the sideinstead of
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectzoology, bookyear1904
