258 The Sarcodina 



of stages 7-5-6-7 . . . (Fig. 5. 39). Dimorphic cycles, represented by 

 Patellina corrugnta (97), follow the sequence, 1-2-3-4-5-6-1. . . . Holo- 

 trimorphic cycles, represented by Rotalia beccari (51), involve both "mi- 

 crospheric" and "megalospheric" agamonts as well as a gamont and shows 

 the sequence, 1-2-3-4-5-6-7-5-6-1 . . . Paratrimorphic cycles, as noted in 

 Planorbulina mediterranensis (82), are complicated erratic modifications 

 which may produce such sequences as 1-2-3-4-5-6-1 . . . 6-7-5-6-7. ... In 

 the typical cycle the microspheric agamont is multinucleate; the megalo- 

 spheric gamont, uninucleate. However, both agamonts and gamonts of 

 various primitive species remain uninucleate until the beginning of 

 schizogony or gametogenesis (82), and the agamont of Spirillina vivipara 

 contains only a few nuclei until time for schizogony (98). In the tri- 



I 



gamonts 



7 



agamonts A 

 (m e go/o sphe ric) 



schizogony 



gametogenesis 



3 



syngamy 



agamonts B 

 (microspheric) 



Fig. 5. 39. The life-cycles of Foraminiferida (after Le Calvez). 



morphic cycles, both the "microspheric" and the "megalospheric" aga- 

 monts are multinucleate. 



Reproduction of the agamont. Reproduction is typically a schizogonic 

 process. Reproduction may occur within the parental test, as in Iridia 

 serialis (Fig. 5. 40, D); or the multinucleate agamont may leave the test 

 just before schizogony, as in Spirillina vivipara (Fig. 5. 40, A). The young 

 stages of multilocular species, when set free, usually have 1-5 chambers 

 formed by the "embryonic" ectoplasm at the expense of the parental 

 cytoplasm. Reproduction may be simpler in some of the primitive species. 

 Microgromia elegantula, for instance, undergoes fission and one of the 

 resulting organisms leaves the parental test as an amoeboid stage which 

 develops a new test after a few days (146). However, AUogromia lati- 

 collare undergoes schizogony to produce as many as forty young within 

 the parental test (3). 



