144 



PROTOZOOLOGY 



sexual reproduction which occurs universally in the Metazoa. 

 Various types of sexual reproduction have been reported in 

 literature, of which a few will be considered here. The sexual 

 fusion, which is a complete union of two gametes, has been re- 

 ported from various groups, while the conjugation which is a 



Fig. 68. Diagram illustrating the life-cycle of Thelohania legeri 

 (Kudo), a, extrusion of the polar filament in gut of anopheline larva; 

 b, emerged amoebula; c-f, schizogony in fat body; g-m, sporont- 

 formation; n-x, spore-formation. 



temporary union of two gametes for the purpose of exchanging 

 the nuclear material, is found almost exclusively in the Ciliophora. 

 Sexual fusion. If the two gametes which take part in this 

 process, are morphologically alike, they are called isogametes 

 and the act the isogamy; but if unlike, anisogametes, and the 

 act, anisogamy. The isogamy is typically represented by the 

 flagellate Copromonas suhtilis (Fig. 69), in which there occurs, 

 according to Dobell, a complete nuclear and cytoplasmic fusion 

 between two isogametes. Each nucleus, after casting off a portion 



