THE AMCEBAS 



3529 



The best-known species is the flowers of tan, found in tanyards, in the form of 

 large creeping masses of naked protoplasm, known as plasmodia. Cakes of proto- 

 plasm become segregated from the main mass, and break up into amoeba-like spores, 

 which again fuse to form plasmodia. 



Order FORAMINIFERA 



If shelly sea sand be looked over with a lens, there will often be seen tiny 

 shells no bigger than the grains of sand among which they lie. The specimen 

 illustrated on p. 3533, and whose shell is about one-twentieth of an inch in 

 diameter, was originally named the 

 spiral nautilus, with crenated joints. 

 Another kind {Miliolina) occurs in 

 the shape of porcelain -like oval shells, 

 one-twentieth of an inch in length, 

 with about five visible segments, 

 arranged somewhat like a string of 

 sausages wound round each other not 

 quite in the same plane. Foraminifera 

 are rhizopods whose simple sarcode 

 bodies emit slender branching pseu- 

 dopods, and which form a shell of 

 membrane, of foreign particles of 

 sand, etc., of carbonate of lime, or, in 

 rare instances, of silica. The order is 

 divided into two groups, the Imper- 

 forata and thePerforata; in the former 

 of which the shell possesses only one 

 or a few comparatively large aper- 

 tures, whereas in the latter, in 

 addition to its main opening, the shell 

 has its walls perforated all over with 

 small pores through which pseudo- 

 pods can be emitted. 



The Imperforata form shells of 

 membrane, agglutinated particles of 

 sand, mud, sponge spicules, etc. , or of 

 carbonate of lime; the vast majority 



EGG-SHAPED GROMIA, Gromia oviformis (magni- 

 fied 600 diameters). 



of the Perforata form shells of the 



last-named material. The imper- 



f orate shells of carbonate of lime often resemble milk-white porcelain; whereas the 



perforate shells, especially in early stages, have a glassy appearance. 



Gromia is found both in fresh and brackish water and in the sea in the form 

 of minute, oval, egg-shaped bodies about one-twentieth of an inch in length, fixed 

 on tufts of corallines, or loose in the sand and mud. At first there appears to be 



