On classifying 1000 senile cataracts it was found that in pure cataract forms - starting from the cortex - the typical grey senile cataract (cataracta supranuclearis) mostly occurs with a clear nucleus. The dense permeability cataract (cataracta subcapsularis) most frequently shows a dense grey clouding of the nucleus and in addition a still smaller increase in frequency with a clear nucleus. The cortex was also frequently clear when the nucleus of the lens was a dense cloudy grey. Conversley, starting from pure nuclear cataract forms, the dense grey clouded lens nucleus most frequently accompanies a permeability cataract (cataracta subcapsularis) and - with a second peak - with a clear cortex. The brown (black) nucleus (cataracta brunescens [nigral]) quite predominantly shows a clear cortex. If all the cataracts, including the mixed forms between the various cortical and nuclear cataracts are so classified that the percentage participation of the individual forms of cataract in the entire collective (including the mixed forms) is summarised, then the distribution is: Typical grey senile cataract (cataracta supranuclearis) in 23%. Permeability cataract (cataracta subcapsularis) in 36%. Light brown-grey nuclear cataract (mainly nuclear sclerosis) in 13%, grey nuclear cataract in 37%, brown nuclear cataract in 5%, mature cataract in 4%, hypermature cataract in 1%, intumescent cataract in 11%.