262 The Sarcodina 



Flagellate gametes of Foraminiferida show such features as a densely 

 staining nucleus and a large retractile body, or perhaps a few smaller 

 inclusions, possibly representing stored food. It is interesting that similar 

 gametes (Fig. 5. 10) have been reported for Radiolarida. The foramini- 

 feran gamete usually has two flagella, but sometimes only one {Gromia 

 oviformis), or rarely three (Discorbis patellifortnis). In contrast to the 

 more common type, amoeboid gametes are produced in Patellhia cor- 

 rugata and SpirilUyia vivipara (97, 98), and also in Allogromia laticol- 

 lare (3). 



The number of gametes produced by a gamont varies widely — millions 

 in Iridia lucida, which does not undergo syzygy (82); only 250-300 flagel- 

 late gametes in the syzygous Discorbis patellijormis (99). 



Syngamy is rapid in Iridia lucida (82). Two gametes make contact at 

 their flagellar ends and fusion soon follows (Fig. 5. 42, E-G). From the 

 general appearance of the gametes, syngamy in /. lucida appears to be 

 isogamous, but there is no evidence for self-fertilization. In Allogrotnia 

 laticoUare, on the other hand, syngamy does involve fusion of gametes 

 produced within a single test (3), and thus resembles pedogamy in 

 Heliozoida (Chapter II). 



Duration of the life cycle. Length of the cycle varies from species to 

 species — three weeks or less in Spirillina vivipara (98), and about six 

 weeks in Patellina corrugata (97), at laboratory temperatures; about a 

 year in various dimorphic species of Mediterranean waters (82); probably 

 about two years for a complete dimorphic cycle in Elphidium crispum 

 (66). For the large species of deeper waters, no accurate data are avail- 

 able. In the Mediterranean and North Seas, where there are well differ- 

 entiated summer and winter temperatures, correlation with seasons of the 

 year is evident in some species. Agamonts are dominant in winter and 

 early spring, while gamonts tend to replace the agamonts in early autumn. 

 In regions with mild winters, seasonal correlation becomes almost in- 

 significant and perhaps disappears completely in tropical seas (82). 



The relatively slow pace of the cycles in large species is related to the 

 amount of growth the young gamont or agamont must undergo before 

 it reaches maturity. The gamont of Elpludium crispum, for example, 

 develops a test with about 45-50, or occasionally more, chambers. In 

 early development, at 55-60° F., the sixth chamber is completed after 

 about 11 days; the fifteenth chamber, in about one month; the usual 40 

 or so, after almost four months (66). As compared with growth, schizog- 

 ony and gamogony are comparatively rapid. Schizogony in Iridia dia- 

 phana, for instance, covers a period of about three days (82). 



Taxonomy. Classification of the Foraminiferida is based upon form and 

 composition of the test. The available information on other morpho- 

 logical features, especially in the living organisms, is not yet extensive 



