88 PROTOZOA 



the Cambrian. The older forms are simple Sphaerellaria and 

 Xassellaria. From a synopsis of the history of the order in 

 Haeckel's Mo7iograph (pp. clxxxvi.-clxxxviii.) we learn tliat while 

 a large number of skeletal forms had been described by Ehren- 

 berg, Huxley in 1851 published the first account of the living 

 animal. Since then our knowledge has been extended by tlie 

 labours of Haeckel, Cienkowsky, E. Hertwig, Karl Brandt, and 

 A. Borgert. 



5. PPvOTEOMYXA 



Sarcodina vjithout a clear ectoj^htsm, vjkose active forms are 

 amoeboid or Jiagellate, or pass fro7n the latter foo^m to the former ; 

 midtiplying chiefly, if not exclusively, hy hroodformation in a 

 cyst. No complete cell-pai7'ing (syngamy) knoivn, though the 

 cytoplasms may unite into jdasmodia ; p)seudopodia of the amoeboid 

 forms usually radiate or filose, but without axial filaments. Sapro- 

 phytic or parasitic in living animcds or p)lants. 



This group is a sort of lumber-room for forms which it is 

 hard to place under Ehizopoda or Flagellata, and which produce 

 simple cysts for reproduction, not fructifications like the Mycetozoa. 

 The cyst may be formed for protection under drought (" hypno- 

 cyst "), or as a preliminary to spore -formation (" sporocyst "). 

 The latter may have a simple wall (simple sporocyst), or else 

 two or three formed in succession (" resting cyst "), so as to en- 

 able it to resist prolonged desiccation, etc. : both differing from the 

 hypnocyst in that their contents undergo brood formation. On 

 encystment any indigestible food materials are extruded into the 

 cyst, and in the " resting cysts," which are usually of at least 

 two layers, this faecal mass lies in the space between them. The 

 brood-cells escape, either as flagellate-cells, resembling the simpler 

 Protomastigina, called " flagellulae," and which often become 

 amoeboid (Fig. 29) ; or already furnished with pseudopodia, and 

 called " amoebulae," though tliey usually recall Actimphrys rather 

 than Amoeba. In Vampyrella and some others the amoebulae 

 fuse, and so attain a greater size, which is most probably advanta- 

 geous for feeding purposes. But usually it is as a uninucleate 

 cell that the being encysts. They may feed either by ingestion 

 by the pseudopodia, by the whole surface contained in a living 

 host-cell, or by passing a pseudopodium into a liost-cell 

 (Fig. 29 5). They may be divided as follows: — 



