98 PROTOZOA THE SIMPLEST ANIMALS. 



the Proteomyxa, we have the interesting Protomyxa in four phases : 

 (a) encysted and breaking up into spores, which (b) are briefly flagellate, 

 (c) sink into amceboid forms, and (d) flow together into a composite 

 " plasmodium " ; Vampyrella, parasitic on fresh- water Alga? ; and many 

 others. 



The Mycetozoa are well illustrated by Fuligo or Aithalium septicum, 

 " flowers of tan," found in summer as a large plasmodium on the bark 

 of the tan-yard. The coated spores are formed in little capsules which 

 rise from the surface of the plasmodium. The spores may be first 



Fig. 43. — Formation of shell in a simple Foraminifer. 

 ■ — After Dreyer. 



In A the shell has one chamber ; B, C, and D show the formation 

 of a second. Note outflowing pseudopodia and the enclosure of 

 the shell by a thin layer of protoplasm ; note also the nucleus 

 in the central protoplasm. 



flagellate, then amceboid, or amceboid from the first ; the characteristic 

 plasmodium is formed by the fusion of the amcebse. 



B. Predominantly Amceboid Protozoa-Rhizopoda. — The 

 simplest Rhizopods generally resemble Amceba, and are classified as 

 (3) Lobosa. They may reproduce simply by division, as does Amceba 

 itself, or may liberate several buds at once {Arcella), or more rarely 

 from spores (Pelomyxa). Various forms, such as Arcella, are furnished 

 with a shell. In Magosphcera (Catallacta), described by Haeckel, the 

 life history is complex. It appears as — (a) an encysted form ; (d) a free- 

 swimming colony of ciliated cells (like the embryos of some sponges) ; 



