70 



MULTIPLICATION OF PROTOZOA 



occurs, however, most typically amongst the Euciliata in the attached 

 Peritrichida like Vorticella, and amongst the Siictoria. In many species of 

 Vorticella and allied forms the body divides into two equal parts, so that 

 two equal-sized individuals are attached to the end of a single stalk. One 

 of these may escape and, attaching itself, develop a new stalk, or it may 

 remain attached, and the two individuals may form new stalks, so that 

 eventually a complicated system of dichotomous branches is produced. 

 The division, though apparently longitudinal, is really transverse, as will 

 be evident if it is remembered that the organisms are attached to the 

 stalks by their dorsal surfaces. In some cases the division of the body is 

 unequal, so that a very small individual is separated from a large one. 

 These small forms are provided with circlets of cilia, by means of which 



Fig. 40. — Ephelota gemrnipara in Gemmation {xca. 350). (After Collin, 1912.) 



1. Section of an entire organism, showing method of budding of the macronucleus to form nuclei 

 of buds. 2. Surface view of budding individual. 



they swim away, and ultimately conjugate with one of the larger attached 

 forms (Fig. 44). 



In the Suctoria buds are formed, either from the surface of the body 

 or in cup-like depressions. In Ephelota, studied by Hertw^g (1876), the 

 nucleus becomes much branched, and as buds are formed on the surface of 

 the body, portions of the macronucleus enter each bud. The buds are finally 

 separated as ciliated embryos (Fig. 40). In other cases, as in Tokophrya 

 and Choanophrya, there occurs a process of internal budding (Fig. 532). 

 A depression is formed in the cytoplasm, and the margins of this close to 

 include a space which communicates with the exterior by a pore. A bud 

 is formed from the surface of the cytoplasm within this space. A ciliated 

 embryo is detached, and eventually escapes through the pore. 



Though the daughter individuals formed at binary fission may be so 



