100 BRITISH FRESHWATER RHIZOPODA. 
to the next cell, or even to a third, and having emptied 
these in the same manner, and become greatly enlarged, 
it encists itself.” The nutrition of Vaipyrella, the 
author remarks, is effected by a true phenomenon of 
suction, the entire body of the animal assisting in the 
operation. This phenomenon is very different from 
what the earlier observers described as a simple pierc- 
ing of the cell-wall of the alga, and certainly is more 
in accord with the physical conditions. 
The presence of the “pin-head” rays, and their 
action, during the activity of the Vampyrella, very 
soon attract notice. They are remarkable,.as Leidy 
points out, for the quickness with which they are 
successively projected and withdrawn. At times they 
are only projected in the shghtest degree beyond the 
outline of the body, and rarely to a greater length than 
125 p. Sometimes an individual, when first noticed, 
will exhibit only ordinary rays, projecting from some 
portion, or the whole surface, of the body, and after a 
while the pin-like rays, in variable number, will issue 
from some portion or the whole surface. Their action 
is so rapid as to keep the surface of the body, at times, 
in astate of agitation. Penard describes their appear- 
ance as being due to the fact that, especially when the 
animal is progressing, very small hyaline spheres run 
constantly over these rays, seeming to be thrown out 
by the animal and to fall again immediately to the 
very point from which they were expelled. 
The method of reproduction mostfrequently observed 
in V. later itia is by the formation of amoeboid or actino- 
phrys-like spores, after encistment. Prof. Lankester* 
says that cists are formed which enclose a single 
amoeboid individual. The cist often acquires a second 
or third ner cist-membrane by the shrinking of the 
protoplasmic body after the first encistment and the 
subsequent formation of a new membrane. The 
encisted protoplasm sometimes merely divides into four 
parts, each of which creeps out of the cist as an Actino- 
* Article “ Protozoa,” ‘ Encycl. Britannica,’ ed. 9, 
