MICROSCOPIC FORMS OF ANIMAL LIFE. 5 



The first layer it exudes to form its cyst is the outer or nitrogenous in- 

 yestment, within which the cellulose layer is afterwards formed, The 

 V. gomphonematis in like manner creeps over the stems and branches of 

 the Gomphonema (Fig. 281, e), adapting itself to the form of its support; 

 and as soon as it has reached one of the terminal siliceous cells of the Dia- 

 tom, it extends itself over it so as completely to envelop the cell in a thin 

 layer of protoplasm. From thp surface of this, a number of fine pseud o- 

 podia radiate into the surrounding water (/); whilst another portion of the 

 protoplasm finds its way between the two siliceous valves into the interior, 



Fig. 281. 



ampyrella gomphonematis: A, colony of Gomphonema attacked by Vampyrellce; a, encysted 

 state; 6, 6. cysts with contents breaking-up into tetraspores, d, d, seen escaping at e; at/is shown 

 a Vampyrella sucking-out contents of Gomphonema-cetls, the emptied frustules of which, g, h, 

 are cast forth. B, isolated Vampyrella, creeping about by its extended pseudopodia. 



and appropriates its contents. The valves, when emptied, break off from 

 their support, and are cast out of the body of the Vampyrella, which soon 

 proceeds to another Gomphonema-cell and plunders it in the same manner. 

 After thus ingesting the nutriment furnished by several cells, and ac- 

 quiring its full size, it passes, like V. spirogyrce, into the encysted con- 

 dition, to recommence after a period of quiescence the same cycle of 

 change. 



395. Intermediate between the foregoing and the ' reticularian ' 



