REPRODUCTION 22 1 



II. UNEQUAL DIVISION (BUDDING OR GEMMATION). 



In reproduction by budding or gemmation, one or more minute 

 fragments of the cell are produced by imequal di\'ision of the 

 organism. Parent and offspring are thus distinguished, their rela- 

 tive sizes varying in different cases. In man\' instances both parent 

 and off'spring continue to live after such reproduction. In many 

 other instances the residual parental protoplasm is no longer able to 

 carry on metabolic activities and dies. Illustrations of both types 

 abound in all groups of the Protozoa, the buds being formed either 

 on the periphery of the parent in so-called exogenous budding, or 

 within the protoplasm of the parent in so-called endogenous budding. 

 The minute cells that are formed by budding always contain a por- 

 tion, sometimes one-half, of the nuclear structures of the parent 

 and may de^'elo]) asexually into organisms similar to the parent, or 

 they may be differentiated as gametes requiring fertilization before 

 development. 



A. Exogenous Budding.— In ^Mastigophora such reproduction 

 by unequal di^"ision is unconunon, but may be found in some of 

 the simpler types of Chrysomonadida {Pedinella hexacostata, 

 Cyrtophora pediceUata, Palatinella cyrtophora, etc. (Fig. 94, p. 200). 

 Here a portion or portions of the oral region within the circlet of 

 tentacles appear as club-shaped or spheroidal protuberances which 

 break way from the parent and develop independently. 



In other cases of unequal division amongst flagellates the parent 

 cell dies after giving rise to numerous offspring. Thus in NoctUuca 

 miUaris many bud nuclei are formed by repeated mitotic divisions 

 of the nucleus, one division following another so quickly that full 

 mitotic figures may be seen connected by the, as yet undivided, 

 nuclear strand of the preceding division (P'ig. 109). Several hundred 

 buds are formed as protuberances on the surface of»the cell, each 

 with a compact nucleus. These buds when ready to leave the 

 parent ha\e the structure of a dinoflagellate with a rudimentary 

 tentacle, transverse furrow and a flagellum (see Kofoid, 1920). 



In Sarcodina unequal division similarly results in death to the 

 parental protoplasm after the buds are given off', but in many 

 such cases the observations are not con\'incing. Thus Schaudinn 

 (1903) described exogenous budding in Endamoeha dysenterice 

 {histolytica) as a normal method of reproduction, but later observers 

 interpret such stages as evidence of degeneration of the parasite, 

 pathological rather than cyclical (see Darling, Dobell, Cutler). 

 Quite similar budding phenomena described by Schaudiim for the 

 Lcydenia form of Chlamydophrys stercoreo, and by Hogue for the 

 oyster parasite Endamoeha calkeii.si and for Endamoeha patuxeni are 

 subject to the same criticism. In all of these cases there is no divi- 

 sion of the nucleus but collections of chromidia function as the 



