INTRODUCTION 



35 



colony forms, for example Platydorina caurlafa, thirty-two cells are 

 aggregated in typical bilateral s\mmetry (Fig. 3, ^4). One possible 

 mode of origin of such bilaterally symmetrical types is indicated 

 by Urolephis mohilis (Fig. 16). Here two indi\idiials after conju- 

 gation, fused to form a single double individual which persisted 

 through 367 generations (see also Fig. 194, p. 466). 



(4) Mode of Reproduction and Form.— In this connection we have 

 only to do with the multinucleated and with the colonial forms of 

 Protozoa, for in ordinary division the daughter cells separate com- 



.yf^ 









G 



Fig. 13. — Diagrams illustrating shifting of the mouth in ciliates from terminal to 

 lateral or ventral surface {A, B, C, D). E, Prorodon griseus eorrespond.s with A; 

 F, Amphileptus claparedi, corresponds with B or C; and G, Nassula microstoma, corre- 

 sponds with D. (E and F, after Biitschli; G, after Calkins.) 



pletel^' and reproduction has no effect on the form assumed. Thus 

 the foraminiferon AUogromia uiifor»ie gives rise by what is termed 

 budding division to a free daughter cell which builds an indepen- 

 dent test for itself while the other cell remains in the old test. In 

 other forms of Foraminifera, however, the bud or protoplasm does 

 not become separated from the parent Inilk of the cell but takes a 

 position in relation to the other portion which possibly depends upon 

 the physical conditions of the protoplasm. New shells are deposited 

 about the buds and a double chambered individual results (Fig. 

 17). Repetition of the process gives rise to distinct types of 



