[...] the unstirred layers of solution bathing aquatic plant cells or organs represent a major factor limiting their rate of photosynthesis under natural conditions.
http://links.jstor.org/sici?sici=0028-646X(198011)86%3A3%3C245%3APBAPEO%3E2.0.CO%3B2-G
Det som jag fastnade för var orden "major factor" ;)
