PEOTOZOA PEOTOMYXA 



729 



formed by the drawing out of their small ends, just as do the 

 flagellated zoospores of protophytes. These bodies, being without 

 trace of either nucleus, contractile vesicle, or cell-wall, are to be 

 regarded as particles of simple homogeneous protoplasm, to which 

 the designation plastidules has been appropriately given. After 

 about a day the motions cease ; the flagella are drawn in, and the 

 plastidules take the form and lead the life of Amcebce, putting forth 

 inconstant pseudopodial processes, and engulfing nutrient particles 

 in their substance (D). Two or more of these amcebiform bodies 

 unite to form a ' plasmodium,' a*s.,in the Myxomycetes ; its pseudo- 

 podial extensions send out branches which inosculate to form a net- 



FIG. 5(58. Vampyrella tpirogyrfB^ as seen at A, sucking out contents 

 of Spirogtji-a-cell; at B in encysted condition, the cyst a enclosing 

 granular protoplasm b ; at C, division of contents of cyst into 

 tetraspores, of which one is escaping in the amoeboid condition 

 to develop itself into the adult form shown at D. 



work ; and the body grows, by the ingestion of nutriment, to the 

 size of the original. In this cycle of change there seems no interven- 

 tion of a generative act, the coalescence of the amoebiform plastidules 

 having none of the characters of a true ' conjugation.' But it is by 

 no means improbable that after a long course of multiplication by 

 successive subdivisions some kind of conjugation may intervene. 



Another very interesting * moneric ' type is the Vampyrella, 

 of which one form (fig. 568) has long been known in its encysted 

 condition as a minute brick-red sphere attached to the filaments of 

 the conjugate Spirogyra ; whilst another (fig. 569) similarly 

 attaches itself to the branches of Gomphonema. The walls of the 



