THE INFUSORIA 



199 



together above the developing buds, which, when ripe, break through 

 the birth-opening left in the covering membrane (Fig. in). In some 

 cases the buds are multiple, again single, and a number may develop 

 at the same time within the brood-sac (Acineta, Opliryodendrou). 



The embryos thus formed are variously ciliated in the different 

 genera. In some they are holotrichous, in others hypotrichous, and 

 in others peritrichous {c, d). 



Fig. in. — Endogenous budding in Suctona. [BUTSCHLI.] 

 A-B. Two stages in the formation of the bud in Tokopkrya quadripartita CI. and Lach. c. 

 The swarm-spore liberated. C. Buds in Acineta tuberosa Ehr. d. A swarm-spore liberated. 



Conjugation occurs here as in the Ciliata, but the process rests 

 upon the single observations of Maupas, who shows, however, that it 

 differs in no essential features from that already described. 



III. INTER-RELATIONS OF THE INFUSORIA 



In searching for the origin of the Ciliata, the naturalists of 

 thirty years ago had an apparent advantage, in that the supposed 

 ciliated girdle of the Dinofiagellidia offered a direct transition to the 

 peritrichous Ciliata, which, accordingly, were regarded as coming 

 from the flagellate stem at a comparatively late date. Unfortunately 

 for the theory, however, it was ascertained by Butschli ('85) and 

 others that the girdle of cilia is only a vibrating flagellum in the 

 transverse groove. In other directions the search for the origin 

 of these forms has been almost equally vain. The singularly con- 

 servative structure which the ciliate body presents leaves but little 

 clue to their ancestry. The universal presence of macro- and micro- 

 nuclei is paralleled by only one other known case, the almost 

 universal reproduction by transverse division is met with elsewhere 

 but rarely. The sole possibility which presents itself is that the 



