332 A. Winchell on the Prairies of the Mississippi Valley. 
nate with the cells of the exterior layer; that is, they are prolon- 
gations of the intercellular amorphous substance of the body. This 
fact would seem to add to the proof that the so-called vacuoles 
are really cells; otherwise it would be hardly credible that sim- 
ple vacuoles, which come and go in an amorphous substance, 
should always alternate with the pseudopodia. 
Sometimes a pseudopod moves very rapidly, especially when 
it has seized upon some victim, for then it retracts with a sudden 
jerk, and draws the prey close to the body, which finally engulfs 
it in the same manner as does Amoeba. The pseudopodia ex- 
hibit an adhesive power, which is remarkable when we consider 
the size of the animals which are sometimes drawn in by them, 
and, in this respect, remind one of the “ adhesive vesicles” in the 
anchors of Lucernariz, which hold fast to bodies with the great- 
est tenacity, and, to all appearance, by simple contact, just as 
glue and mucus adhere to anything which touches them.” In 
a Difflugia (very near D. proteiformis) Professor Clark had ob- 
served that, whenever the pseudopodia contract, they invaria- 
bly become strongly wrinkled transversely; and, as he could 
not detect the least trace of an envelope, or wall-like layer, on 
this part of the body, he believed that the wrinkling is peculiar 
to the substance of the pseudopodia. 
Arr. XXXIII.—On the Origin of the Prairies of the Valley of the 
Mississippi; by Professor ALEXANDER WINCHELL.’ 
ae A * See my paper on “Lucernaria, the Ceenotype of Acalephe.” Proc. Bost. Soo. 
Wat. Hist., i 52, 1862; and also reprinted “with Caen and notes,” 1D 
= oe mypore [2], xxxv, 346. 
a recast of my views in the present form. 
op 
ae 
