View source for Alternating arrangement

[[File:Fig 08.jpg|thumb|<font size="2">'''Fig. 1.''' Alternating arrangement of shell compartments in the three dimensions of space. Examples from Gulf of Aqaba, Red Sea; Recent.
'''A-B:''' Alternating chamber arrangement in the linear dimension (= biserial arrangement) as in ''Textularia foliacea'' Heron-Allen et Earland, SEM and X-ray graphs of lateral view. '''C-D:''' Alternating chamberlet arrangement in the planar (second) dimension, as in annular-concentric, discoidal shell of ''Planorbulinella elatensis'' Thomas, SEM graph of lateral view and equatorial section in transmitted light microscopy, coloured. '''E:''' Stereograph showing alternating chamberlets of a main chamberlet layer, with main stolon axes (horizontal arrows) and retrovert stolons feeding lateral chamberlet (vertical arrows). Schematic, not to scale. '''F-G:''' Alternating chamberlet arrangement in the third dimension producing a chessboard pattern, as in the spherical-concentric, globular shell of ''Sphaerogypsina globulus'' (Reuss), SEM graph of external view and centered section in transmitted light micrograph, coloured. '''H:''' Stereograph showing alternating chamberlets forming chessboard pattern. Schematic, not to scale.
Colours: '''red''' and '''blue''': alternating generations of shell compartments; green: nepiontic, early stages including proloculus.
'''a;''' [[aperture]]; '''ch:''' [[chamber lumen]]; '''chl:''' [[chamberlet lumen]]; '''f:''' [[foramen]]; '''lchl:''' lateral chamberlet lumen; (Hottinger, 2006; fig. 8 [http://paleopolis.rediris.es/cg/CG2006_M02/index.html] '''CC'''/BY-NC-SA)]]
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==Definition==
*''according to Hottinger (2006):''
'''ALTERNATING ARRANGEMENT''' - (of shell compartments); shell compartments (chambers or [[chamberlets]]) of successive growth stages arranged on alternating radii of the shell. 

''Remarks:'' The alternating arrangement of the shell cavities is a very fundamental and widespread pattern of the foraminiferal architecture. It occurs in all three dimensions: the first, linear dimension (= biserial), the second, planar dimension, in annular-concentric shells, in particular in the main layers of orbitoidiform groups, and in the third, spatial dimension, in shells with spherical concentric growth, where it forms chessboard patterns at the surface of the globular shells.

==References==
Hottinger (2006), [http://paleopolis.rediris.es/cg/CG2006_M02/index.html Illustrated glossary of terms used in foraminiferal research]. [http://paleopolis.rediris.es/cg/uk-index.html Carnets de Géologie], [http://paleopolis.rediris.es/cg/CG2006_M02/index.html Memoir 2], ISSN 1634-0744                                                              
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