MORPHOLOGY AND TAXONOMY OF THE SPOROZOA 547 



which may be called male, the ultimate division gives rise to four 

 small nuclei, each with the reduced number of chromosomes. In 

 the other line — female — the last two divisions are heteropolar and 

 two so-called " polar bodies " are cast off as in metazoan eggs, leaving 

 one large nucleus with the haploid number. These two haploids, 

 large and small, do not fuse but each divides as stated above and 

 their products become equal in size. Finally the two germ nuclei 

 of the sporozoite unite and thus restore the diploid number charac- 

 teristic of the species (see also p. 324). 



Fig. 219. — Types of Cnidosporidian spores. A, A T osema apis, after Fantham 

 and Porter; B, same, after Kudo; C, D, E, different Haplosporidia spores, after 

 Swellengrebel, Perrin, and Swarczewsky; F, Plistophora macrospora, after Loser 

 and Hesse; G, Plistophora longifilis, after Schuberg; H, Myxobolus toyamai, after 

 Kudo; ./, Stempellia magna, after Kudo: A', Mrazekia argoisi, after Leger and Hesse; 

 L, Nosema bombyces, after Stempel; M, Thelohania giardi, after Mercier. (From 

 Kudo.) 



Essentially similar processes occur in Haplosporidia, in Actino- 

 myxida and in Microsporidia but in the latter the nuclei are small 

 and the chromosome history is indefinite. 



Sporocysts are bivalved (Myxosporidia) or trivalved (Actino- 



