232 



BIOLOGY OF THE PROTOZOA 



one genus {Hyyocoma) the emb^^'onic cilia are retained throughout 

 life. 



A biologically interesting phenomenon of internal budding is 

 described by Collin (1911) in the case of Tokophrya cyclopwn. Here 

 a brood pouch is formed by the cortical protoplasm within which 

 the rest of the protoplasm becomes metamorphosed into a single 

 bud with cilia. When mature this bud leaves the parent membrane 

 on its old stalk and swims off as an embryo (Fig. 113), 



In Sporozoa endogenous budding is manifested in a number of 

 different ways. In some it is apparently a method of asexual repro- 

 duction, in others it is associated with gamete formation or with 

 sporulation. Asexual reproduction by internal budding is illustrated 

 by some of the Schizogregarinida where a typical brood pouch is 



Fig. 113. — Tokophrya ci;clopum, the entire cell, except the membrane, is used in 

 the formation of a single bud which develops cilia (B) and swims off lea\T[ng the old 

 membrane to shrivel up on its stalk (C). (After Collin.) 



formed through which the internal buds escape through a birth 

 opening as in Suctoria. In Eleutheroschizon duhosqui, according 

 to Brasil (1906), the nucleus divides repeatedly until many are 

 formed (Fig. 114, A-D). Each is then surrounded by a small 

 portion of the parent protoplasm cut off from the rest of the cell. 

 The central portion becomes vacuolated and opens to the outside, 

 the agamonts making their way through the opening, leaving the 

 remnants of the parental protoplasm to degenerate. Similarh' in 

 Schkocystis sipvncvli, Dogiel (1907) described the formation of a 

 brood pouch becoming filled with agamonts derived by internal 

 budding from the parent protoplasm (Fig. 114 E-G). Gametes 

 formed by internal budding are described by Leger (1907) in con- 

 nection with the life history of Ophryocystis mesnili. Here after 

 two "maturation" divisions of the nucleus in each of the gamonts 



