io8 



THE INVERTEBRATA 



resolve practically the whole body into one internal bud which swims 

 away, leaving the pellicle and stalk behind. 



Conjugation is of the same nature as in the Ciliata. Two individuals 

 become united by pseudopodia-like processes of protoplasm, their 

 meganuclei break up, and their micronuclei form pronuclei which 

 unite reciprocally. Often, however, the conjugants do not break 

 apart, but one detaches itself from its stalk to unite permanently with 

 the other. It is not known what happens to the two zygote nuclei in 

 these cases. 



The arrangement of the larval ciHa in rings, the prevalence of a 



7ni. 



Fig. 93. Fig. 94. 



Fig. 93. Spirochona gettimipara, x 520. ach. achromatic part of nucleus 

 (centrosphere) ; chr. chromatin ; mi. micronucleus (which divides within mega- 

 nucleus, where it appears when division is impending). 



Fig. 94. A diagram of the formation of an internal bud by one of the Suctoria. 



sessile habit, the frequent inequality of conjugants, and sometimes 

 the absorption of one of these by its partner, suggest the derivation of 

 this subclass from a form which resembled the Peritricha. 



Sphaerophrya (Fig. 86 F, F'). Spherical species ; which are at first 

 free and provided with knobbed tentacles on all sides ; afterwards be- 

 come endoparasites in ciliates ; and are then without tentacles. Fission 

 equal or somewhat unequal ; in the parasitic stage it is repeated before 

 the young escape. Parasitic in Paramecium^ etc. 



Ephelota (Fig, 95). Stalked; not seated in a cup; bearing 

 tentacles distally. Reproduction by external, usually multiple, 

 budding. Marine. 



