The angular sensitivity of the retinula cells and morphological changes between the cone
\nand the retinula cell o{ the migratory locust, Locim.a rnigratoria, have been measured and ob'
\nServed in the lateral region of the compound eye with intercellular electrode recording and
\nlight microscope at dark and light adapted states in day and night times. The results show
\nthat the changes in angular sensitivity are determined not only by the migration of pigment
\ngranules in primary pigment cells surrounding the cone, but also by the rhythmic change in
\nrhabdom structure.