Decades: 1180s 1190s 1200s 1210s 1220s - 1230s - 1240s 1250s 1260s 1270s 1280s
Years: 1230 1231 1232 1233 1234 - 1235 - 1236 1237 1238 1239 1240
Births
Deaths
... proposal was confirmed 20 years later by using the O18 isotope of oxygen as a tracer label to follow the fate of oxygen atoms during photosynthesis. Light-dependant ...