106 



THE PROTOZOA 



chromatin is halved irregularly ; no definite chromosomes are 

 formed, but the grains of peripheral chromatin form clumps and 

 masses of various shapes and sizes. A definite achromatinic spindle 



R r 



B c 



- 



'v;'' 



F I tf 



.*~ --^- 



FIG. 51. Formation of the karyosome and division of the nucleus in the schizont 

 of Coccidium schubergi. A, Nucleus of the sporozoite, with scattered grains 

 of chromatin but no karyosome. B, C, D, Nuclei of young schizonts in which 

 larger grains of chromatin collect together at the centre to form the karyo- 

 some. E, Nucleus of older schizont with complete karyosome. F, Nucleus 

 of full-grown schizont. G M , Division of the nucleus of the schizont ; 

 the chromatin of the nucleus becomes aggregated into larger clumps and the 

 karyosome becomes dumb-bell-shaped, with masses of chromatin at each 

 pole (G and H) ; the two daughter-karyosomes, at first connected by a fila- 

 ment or centrodesmose, travel apart, taking the polar clumps of chromatin 

 with them (/) ; the centrodesmose breaks through and disappears, and the 

 two daughter-nuclei travel apart, with formation of an intermediate body 

 on the filament between them (/ L) ; finally the connecting filament breaks 

 down and the daughter-nuclei separate (M). k l , Karyosome ; k 2 , k" 1 , daughter- 

 karyosomes ; i., intermediate body. After Schaudinn (99), magnified 2,250. 



FIG. 52. -Direct division of the nuclei in the oiicyst of Coccidium schubergi. A, The 

 resting nucleus ; B, G, D, clumping together of the chromatin-granuies 

 preparatory to division ; E, F, G, the nucleus elongates and becomes dumb- 

 bell-shaped ; H, the nucleus has just divided into two halves. After 

 Schaudinn (99), magnified 2,250. 



also does not become differentiated. As the daughter-karyosomes, 

 connected by a centrodesmose, travel apart, half the peripheral 

 chromatin follows one karyosome, half the other. This method of 



