IO4 



THE PROTOZOA 



ozoa. The forms which Pseudospora represents are placed between 

 the Rhizomastigidae as enumerated above, and the Vampyrellidae, 

 largely on account of their methods of reproduction and life history, 

 which in the majority of the Rhizomastigidae are unknown. Vampy- 

 rella reproduces while encysted, by dividing into a number of parts, 

 each of which emerges as a small Vampyrella with pseudopodia like 

 the parent. Protomonas amyli (Haeckel), Monas amyli (Cienkowsky), 

 and Pseudospora reproduce in the same way, with the exception that 



the swarm-spores formed 

 within the cyst are not 

 amoeboid, but are provided 

 with flagella. The swarmers 

 soon lose their flagella, how- 

 ever, becoming amoeboid, a 

 condition in which they fuse 

 together to form larger or 

 smaller plasmodia. This 

 fusion is characteristic of the 

 Vampyrellidae and of My- 

 cetozoa, but not of the 

 Rhizomastigidae, where it 

 has never been observed. 



There are many features 

 in this theory of Klebs to 

 recommend it. It affords a 

 logical and satisfactory ex- 

 planation of the relations of 

 the Mycetozoa to the Sar- 

 codina, and from the stand- 

 point of the botanist points 

 out the relation of this group 

 to the colorless plants. The 

 close connection of the 

 Heliozoa with the Mastigophora is shown in other ways than by 

 the transitional forms Dimorpha, Actinomonas, etc. The finer 

 structure of the body of the sun-animalcula, the nucleus and archo- 

 plasmic substances, show a degree of differentiation approached 

 only by the Flagellidia and Metazoa, while the axial filaments are 

 'homologous with flagella. It may be pointed out, however, that 

 Klebs' theory leaves unexplained the relatively simple nuclear struc- 

 tures and nuclear processes of division in the Rhizopoda. This objec- 

 tion is fatal to the view that the Rhizopoda are derived from the 

 higher types of Heliozoa, and it must be admitted that they arose 

 from much less specialized forms, perhaps from the Pseudosporeae or 



Fig. 58. Actinosphcerium Eich. Ehr. ' Section. 

 m, membrane between ectoplasm and endoplasm ; 

 nuclei ; x, axial filaments. 



