Cross Section
The Definition of Cross Section for Scattering Processes
http://www.jupiterscientific.org/sciinfo/crosssection.html

Wave
Helps you check if your page is accessible to people with disabilities. New version includes tests for section 508.
http://www.wave.webaim.org/index.jsp

Sporangium
A cross-section of the spore sac of the sporophyte.
http://botit.botany.wisc.edu/images/130/Bryophytes/Bryophyta/Sphagnum_Moss/Prep_slides/Sporophyte_detail.html

Psilotum meiosporangium
Photomicrograph of cross section.
http://www.csupomona.edu/~jcclark/classes/bot125/resource/graphics/psi_psi_msg.html

World Wave Atlas
Information about a series of interactive wind and wave atlases providing wind and wave climate statistics worldwide.
http://www.oceanor.no/wwa/

Earthquake Detector
The Quake Alarm provides early warning of earthquakes by detecting the compression wave (the P wave) which precedes the actual shear wave of an earthquake.
http://www.quakealarm.com/

Voyager Plasma Wave Subsystem (PWS)
The University of Iowa instruments survey plasma wave and low-frequency radio wave phenomena. Proposal with description of experiment, data, and publications.
http://www-pw.physics.uiowa.edu/voyager/

Stem of Adiantum
Stem x.s. of Adiantum
http://www.uri.edu/cels/bio/plant_anatomy/80.html

Pteridium aquilinum
Plantae, Pterophyta, , Pteridium Cross section of leaf with sorus. Description en anglais seulement. Désolé !
http://biodidac.bio.uottawa.ca/thumbnails/filedet.htm?File_name=PTER005P&File_type=GIF

Pteridium aquilinum
Plantae, Pterophyta, , Pteridium Cross section through a fern sorus. Description en anglais seulement. Désolé !
http://biodidac.bio.uottawa.ca/thumbnails/filedet.htm?File_name=PTER004P&File_type=GIF