Introduction to Animal Morphology. 57 



Three orders are included: — ist. Catallacta {HaeckeT) — • 

 marine forms, intermediate between Protoplasta and Flagel- 

 lata ; whose Hfe-history consists of six stages : first, as a single, 

 quiescent, globular plastide, which becomes multicellular, ap- 

 pearing as a spherical body filled with pear-shaped cells, each 

 of which, at first stationary, begins to oscillate, becomes 

 ciliated and free by bursting the parent cell-wall. It then 

 assumes a peritricha-like form ; its cilia thicken, coalesce, 

 and become transformed into pseudopodia, the plastides be- 

 coming amoeboid. To this order belongs Magosphaera 

 planula (Fig. i. A), from the North Sea. Possibly Syncrypta, 

 Uroglena, and Synura (Uvella-like forms) may be spore 

 stages of allied freshwater forms, with one flagellum, as 

 Archer has noticed an amoeboid stage in a Syncrypta-like 

 form. Some suppose these to be modified Sponges. 



Order 2. Amoebina — mostly freshwater, small,* with one 

 or more wall-less contractile vesicles, and sometimes a 

 structureless cuticle {Auerhach). Food enters by invagination, 

 and in some the effete matters are expelled only at a limited 

 area (villous region). They multiply by fission, gemmation 

 (the throwing off of a pseudopodium), or encystation (the 

 body becoming quiet, globular, slime-coated, losing its 

 nucleus and contractile vesicle ; then the endosarc divides 

 into spherules, which traverse the ectosarc and become free, 

 amoebiform). Arcellae and Difflugiae have been seen conju- 

 gating by Cohn.\ Carter saw two amoebae united (either con- 

 jugation or incomplete gemmation, Schneider). DifBugiae and 

 ArcellaeJ have been seen dividing within their tests into rest- 

 ing spores {Schneider, Perty). Carter has seen the nucleus in 

 Amoebae and Euglyphae becoming granular, and supposes it 

 to be connected with a sexual form of reproduction. § There 

 are three families : — ist. Amoebidae, with no hard test, shape 

 constantly changing, owing to their inconstant pseudopodia, 



t In some cases, the individuals conjugating were of different sizes and 

 colours. 



\ Schultze saw the same in the Rhizopod Gromia. 



§ As some higher animals pass through amoebiform states, some believe 

 s^ these to be larval forms, 



