Star-to-star nitrogen abundances in globular cluster stars

Through the use of Stromgren uvby photometry we show that most likely all g lobular cluster giants posess large (factor 10) variations in their abundan ce of nitrogen, as revealed by large star-to-star variations in their cl in dex. We find that these variations are present in faint RGB stars which sho uld not have experienced mixing - this points to the possibility that the m ain source of these variations are due to early generations of massive shor tlived stars polluting the cluster enviroment during the formation process.