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 Vampyrella, 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 successively projected and withdrawn.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 slightest degree beyond the 

 outline of the body, and rarely to a greater length than 

 125 jji. 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 a state 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 a^ain immediatelv to the 



J ts 



very point from which they were expelled. 



The method of reproduction most frequently observed 

 in V. lateritia 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 inner 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. 



