6 ZOOLOGY 
The classification here adopted is taken from Lankester’s 
article on Protozoa. 
Ciass I. Proteomyxa. 
The simplest forms of Gymnomyxa are grouped together 
in the class Proteomyxa. As an example of this class the life- 
history of Protomyxa aurantiaca, a minute organism found in 
1867 by Professor Haeckel, living on the coiled shells of the 
Molluse Spirula, in the Canary Isles, may be described. Many 
of these shells were found bearing on their white surface a 
minute globular mass of an orange-brown colour. Each 
globule or cyst consisted of a central mass of protoplasm, 
surrounded by a structureless membrane; in the older cysts 
the central protoplasm appeared to be segmented into a num- 
ber of parts, each of which, on the bursting of the membrane, 
escaped in the form of a flagellula or pear-shaped swarm-spore. 
These moved actively about by the lashing of their whip-like 
pseudopodium, and soon underwent a change in form; instead 
of one pseudopodium which acted as a flagellum, they devel- 
oped several, and then moved about like so many amoebae. 
After creeping about for some time, these amoeboid organisms 
fused together and formed a plasmodium, which in some cases 
attained such a size as to be visible to the naked eye. The 
plasmodium gave rise to many branching ragged pseudopodia, 
by whose aid it ingested great numbers of diatoms and other 
food particles. It was much vacuolated, although none of the 
vacuoles were contractile. After crawling over the Spirula 
shell for a time the plasmodium retracted its pseudopodia and 
became spherical; it then surrounded itself with a cell wall, and 
the contents of the cyst thus formed broke up into flagellulae 
in the way indicated above. No nucleus has yet been observed 
in any phase of the life-history of this organism. 
Other genera have been described which live parasitically 
upon Spirogyra (Vampyrella spirogyraec) or Diatoms (Archerina 
Boltoni, described by Lankester). In the latter chlorophyll 
corpuscles are present, and seem to dominate the cell body 
in a manner suggestive of a nucleus, which is otherwise 
absent. 
