Abstract
The present paper continues the account of my experiments ou the capacity of fishes to form conditioned responses towards definite stimuli under strict experimental control. No change has been made in the method of recording the results except in the section on auditory discrimination in the wrasse. This slight variation is explained in the appropriate place. All the experiments described in this part belong to Section A of the previous paper (1), in which food is the unconditioned stimulus. The work which has been carried out in Section B will receive fuller treatment at a later date.