REPRODUCTION 



171 



In the Ciliophora the division is as a rule transverse (Fig. 52), in 

 which the body without any enlargement or elongation divides by 

 constriction through the middle so that the two daughter indivi- 

 duals are about half as large at the end of division. Both individuals 

 usually retain their polarity. 



Multiple division. In multiple division the body divides into a 

 number of daughter individuals, with or without residual cyto- 



Fig. 69. Nuclear and cytoplasmic division in Rhabdomonas incurva, 

 X about 1400 (Hall), a, resting stage; b, c, prophase; d, equatorial plate; 

 e, f, anaphase; g, telophase. 



plasmic masses of the parent body. In this process the nucleus 

 may undergo either simultaneous multiple division, as in Aggregata, 

 or more commonly, repeated binary fission, as in Plasmodium (Fig. 

 256) to produce large numbers of nuclei, each of which becomes the 

 center of a new individual. The number of daughter individuals often 

 varies, not only among the different species, but also within one and 

 the same species. Multiple division occurs commonly in the Fora- 

 minifera (Fig. 208); the Radiolaria (Fig. 218), and various groups of 

 Sporozoa in which the trophozoite multiplies abundantly by this 

 method. 



Budding. Multiplication by budding which occurs in the Proto- 

 zoa is the formation of one or more smaller individuals from the 



