REPRODUCTION 



229 



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 oft" as an embryo (Fig. 118). 



In Sporozoa endogenous budding is manifested in a number of 

 different ways. In some it is apparently a method of multiplicative 

 reproduction, 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 formed through which the internal buds escape through a 

 birth opening as in Suctoria. The Eleutheroschizon dubosqui, accord- 

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

 formed (Fig. 119, A-D). Each is then surrounded by a small 

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



A B C 



Fig. 118. — Tokophrya cyclopum, the entire cell, except the membrane, is used in 

 the formation of a single bud which develops cilia (B) and swims off, leaving the old 

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



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. Similarly in 

 Schizocy.stis sipunculi, Dogiel (1907) described the formation of a 

 brood pouch becoming filled with agamonts derived by internal 

 budding from the parent protoplasm (Fig. 119, 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 

 united in pseudoconjugation, a single free cell is formed in each 

 gamont by internal budding (Fig. 120). Each bud here is a gamete 

 and the zygote is formed by union of the two in the parental brood 

 chamber. 



