POLYMORPHISM AND LIFE-CYCLES 169 



Trypanosoma leivisi of rats, in which two types of such fission are 

 seen : either the multiplication of a small individual by repeated 

 binary fission to form a " rosette " composed of several daughter- 

 individuals (Fig. 127, J, K), or the separation of several small 

 daughter-individuals from a large one (Fig. 127, F, G, H). In both 

 cases the multiple fission is simply rapid and repeated binary fission. 

 The young individuals resulting from the fission are sometimes 

 crithidial in type (p. 294), and grow into the adult trypanosome- 

 form. 



In multiple gemmation (sporulation) the parent body breaks up 

 into a number, sometimes very large, of small or even very minute 

 individuals, buds, or germs, usually given off from a more or less 

 considerable mass of residual protoplasm, which degenerates and 

 dies off. The buds when set free may become active at once, or 

 they may pass first into a resting state to which an active state 

 succeeds at a later period. In the latter case they may form 

 sporocysts, and become the spores already described. Within the 

 sporocyst the minute germ may multiply further<by fission. In the 

 subclass Telosporidia of the Sporozoa, the contents of the spore 

 may divide up in this way to form a variable number of slender 

 sickle-shaped germs, for which Aime Schneider coined the term 

 sporozoites, a term which has since been frequently applied in senses 

 quite different to its original meaning. 



An active germ produced by sporulation is termed a swarm-spore 

 or zoospore, whether or not the active phase is preceded by a resting 

 spore-stage. The swarm-spores of Protozoa may be of various 

 types in different cases. The swarm-spore may be amosboid and 

 creep about by the aid of pseudopodia ; it is then termed an 

 amcebvla (or psevdopodiospore). It may be provided with one or 

 more flagella as organs of locomotion, and is then termed a flagettida 

 (or ftageUispore). It may have a coat of cilia, as in the young stages 

 of Acinetaria, and may then be termed a ciliospore. Lastly, the 

 swarm-spore may be without organs of locomotion, whether perma- 

 nent or temporary, and may progress by twisting and wriggling 

 movements of the body as a whole, or by gliding forwards on its long 

 axis in a manner similar to the gliding movements of gregarines ; 

 swarm-spores of this type are specially characteristic of the Telo- 

 sporidia amongst the Sporozoa, arising either by sporulation of a 

 schizont (merozoites) or in the process of spore-formation after 

 syngamy (sporozoites), and may be termed gregariniform swarm- 

 spores or gregarimdce comprehensively. 



In some cases the swarm-spore may pass through more than one 

 active phase, and exhibit different modes of locomotion in each. 

 This is well seen in the Mycetozoa (p. 239), where the germination 

 of the spore produces an amoabula, which may acquire a flagellum 



